I will say this from the start: I never expected the Witch Doctor to be so much fun. I had always viewed this class as a sort of Necromancer Plus, and Diablo 2's Necromancer never managed to capture my attention.
After playing the Witch Doctor in the beta to the maximum level of 13, my opinion of this class improved to a high degree.
The Witch Doctor is a combination of several archetypes. I see it as a ranged class because most of its offensive skills are used at range. Yet, some of these skills are only medium range, which sometimes may put the Witch Doctor closer to the action than he/she would like. On the other hand the Witch Doctor is also a summoner with its multitude of creepy minions. Thirdly, the Witch Doctor has access to some of the most powerful and effective debuffs (or curses) in the game. Now you may argue that the Necromancer also had these 3 traits, to which I will reply that you are right, but the Witch Doctor really is a Necromancer on steroids.
The Witch Doctor uses a resource type that's very familiar to most RPG players: Mana. Mana is very straightforward: you use it to power your skills and spells. In Diablo 3, Mana has a fast recharge rate (which can be further increased by some passives), although it is not as fast as, say, the Wizard's Arcane Power. The Mana pool also increases with level.
Read my quick primer on how skill slots work in Diablo 3, if you don't know that already.
Next is a review of all the skills and runes in the beta, broken down by skill slot, with the usual disclaimer that these are my own opinions and tastes.
Primary (left mouse - slot unlocked at level 1)
Lv 1 - Poison Dart
Poison Dart is the first skill you start the game with, and it's deceptively simple. For a negligible Mana cost (I don't understand why it's not free), it fires a single dart which does 100% weapon damage in the form of poison. On its own, this skill doesn't shine, but once you start adding runes to it, it doesn't become half bad. I have tried a couple of different Witch Doctor builds in the beta and one of them still uses Poison Dart (runed) at level 13.
Lv 6 - Rune - Splinters
For your first Witch Doctor rune, you get Splinters, which augments Poison Dart. Now instead of firing 1 dart for 100% weapon damage, you will fire 3 darts for 60% damage each, or a total of 180% damage. Not bad, considering that your 2nd or 3rd dart can hit monsters behind the first one killed by your barrage. Besides, Poison Dart runed with Splinters is pretty good for smashing urns and stuff, as you can smash several of them in a row, with just one shot.
Lv 13 - Rune - Numbing Dart
I will admit that I didn't try Numbing Dart at all, and the reason is simple: all this rune does is it causes Poison Dart to slow the enemy by 60% for a paltry 2 seconds. I really don't see the point of this rune, at least not in the beta and maybe not outside PvP. Either way, I think it needs an upgrade, if people are to use it. Either increase the slowing effect, its duration, or both. But in the beta, Poison Dart is not exactly a speed demon, meaning that before you can hit multiple enemies with it, the slowing effect will wear off on the initial ones.
Lv 3 - Corpse Spiders
I started out skeptical about this skill but later on I incorporated it in one of my two builds. The base skill itself is quite annoying and I don't recommend using it before you can slap a rune on it. What it does is, the Witch Doctor throws a jar which breaks, releasing 4 spiders which attack for 16% weapon damage (64% total?) "before they die". It's unclear how long their lifespan is and how many attacks they manage during that time. Suffice to say that the throwing animation makes this skill feel very slow and unwieldy, especially when it is assigned to the primary mouse button. Also, the spiders aren't exactly champion sprinters. They just skitter towards the target at a comfortable speed.
Lv 9 - Rune - Leaping Spiders
Leaping Spiders greatly improves Corpse Spiders. Now, instead of crawling to the target, the spiders effectively leap at it (think Alien facehugger), which makes the skill feel a lot more responsive. Furthermore, the spiders' damage is increased a little to 19% weapon damage and the distance they can jump is also increased to 25 yards. I have managed to improve the feel of Corpse Spiders even more by turning Elective Mode on and assigning this to the "2" key. This allowed me to effectively spam the skill by punching the key repeatedly. The jar will break where your mouse pointer is. The cool thing about this skill is that the Mana cost is only 5 (which is nothing, as Mana regenerates much quicker than you can use it with the skill), and you can spam it indefinitely. A favorite trick is to cover the ground in spiders before a boss appears or spawns, and when he does, he'll be covered in creepy-crawlies.
Lv 11 - Plague of Toads
Although I've seen many people use Plague of Toads, I couldn't warm up to it. It feels a bit like Corpse Spiders but even though the tooltip says 130% weapon damage (which is a lot more than Corpse Spiders), it didn't seem as effective to me. Coupled with the fact that it's much shorter range and a lot more inefficient (34 Mana a pop), it quickly fell off my radar. Unfortunately there aren't any runes for it in the beta but I'm sure later on it will be augmented in more interesting ways.
Secondary (right mouse - slot unlocked at level 2)
Lv 2 - Grasp of the Dead
Five minutes into your new Witch Doctor you will reach level 2 and also one of the skills that I absolutely adore. I have found Grasp of the Dead indispensable in my short career, and both of my builds feature it. So what does it do? 1) You can place it wherever your cursor is, including at the edges of the screen, so the range is practically unlimited; 2) It slows enemies by 60% in a fairly large radius; 3) It also deals Damage over Time (DoT) to all the monsters inside its radius. The tooltip says 20% weapon damage (as physical) over 8 seconds (which is both the duration and the cooldown of this skill), but does that mean 20% each second, or 20% spread over all 8 seconds? To me it seems it's the former, because monsters are chewed to shreds inside the circle. As I said, I love this skill. There might be better skills out there but I have a feeling I will make room for this even at level 60. Oh and the Mana cost is 122, but the Mana will recharge fully during the 8 seconds in which the skill is on cooldown. The one "flaw" of Grasp of the Dead? The cooldown. It would have been really cool if it didn't have a cooldown and you could spam it, limited only by your mana, but I guess that would have made it overpowered.
Lv 7 - Rune - Groping Eels
Groping Eels is a very good - and straightforward - addition to Grasp of the Dead. It increases the DoT from 20% to 26%. It makes a great skill even better and you can equip it very early, at level 7.
Lv 5 - Firebats
Here's another cool skill. Firebats is like your personal flamethrower. Hold the mouse down and spew a constant stream of flames in the form of bats, which deal 150% weapon damage as fire. The downside? It will gulp all your Mana in a few seconds. Also, the range isn't that great. I recommend using it only when monsters are packed close together, or otherwise wait for the rune at level 11.
Lv 11 - Rune - Dire Bats
Dire Bats improves upon Firebats, such that I use it in both my builds. Instead of a stream of flaming bats, you will now fire a single large fiery bat which has much bigger range (40 yards, which is effectively the edge of the screen) and does more damage (220%). What I like about this skill is that the bat feels partially guided. It won't seek out monsters but if you fire it in close proximity to a monster or group of them, it seems to maneuver towards them. It will also pass through several monsters and damage all of them, though I haven't exactly determined how that works. Thanks to its huge damage, this rune allows Firebats to be very useful for AoE-ing large packs of monsters and it also works well on bosses. Although the rune doesn't improve Mana efficiency, it does make it feel more economical due to the fact that you don't hold the button down anymore.
Lv 12 - Haunt
Haunt is featured in one of my builds. At first sight it does massive damage: 575% weapon damage as arcane. The catch? That damage is spread over 15 seconds, however the Mana cost is very decent, only 98. When I first tried Haunt I wasn't very impressed because the effects aren't obvious immediately. It takes some time for this skill to work its magic (haha get it?) but it has a couple of aces up its sleeve that make it worthwhile. For one thing, this is a guided missile. It will seek out monsters in the general direction of your mouse pointer. You don't have to be precise. For another, if the monster dies while the DoT is in effect, Haunt will jump to (and afflict) another nearby enemy. It is unclear whether the DoT is reset on the new enemy or it starts where it left off on the previous one. I find Haunt great because I can spam several of them on different monsters (you can also target specific monsters if you want) and then run around kiting them. I have a feeling that it will be great for tough bosses, where you can endlessly run from them, occasionally refreshing Haunt.
Defensive ("1" key - slot unlocked at level 4)
Lv 4 - Summon Zombie Dogs
Zombie Dogs is another popular skill and it's the first summoning spell that Witch Doctors get, and early on at that. It summons 3 of these critters that follow you around and damage your foes. All fine and dandy, until you meet a tough boss like the Skeleton King. That's one of the weaknesses of Zombie Dogs: they die quickly on harder bosses. Another weakness is that they have a long cooldown (60 seconds), meaning that you can't re-summon them repeatedly when they die. Third weakness is that their damage doesn't seem to be that great. For that reason, I am not thrilled with them in the beta. There are passive skills which improve all your pets and runes also help to make them more useful so maybe they will be a lot better later on.
Lv 12 - Rune - Rabid Dogs
Luckily in the beta we also get access to the first rune for Zombie Dogs. Rabid Dogs colors your critters a bright green, which is a great improvement over the drab grey they start out as. More importantly, they also get a DoT, on top of their usual damage, which deals 9% weapon damage (your weapon, not theirs) over 3 seconds. It doesn't seem like much but it is something. I haven't noticed much difference but at this level my Witch Doctor is too powerful for most monsters anyway.
Lv 8 - Horrify
Horrify is the most basic type of defensive spell. It makes all monsters inside 12 yards run away in fear for 4 seconds. I've only used it a couple of times, so I can have an excuse to talk about it here but in the beta I don't see the utility. I'm sure it will prove useful at higher difficulty levels, when survival becomes very important, or in PvP. Unfortunately the cooldown is long (20 seconds) and though there's a passive skill which reduces this by 2 seconds, I think that's not enough, so even in Inferno I doubt I'll use this.
Terror ("2" key - slot unlocked at level 9)
Lv 9 - Soul Harvest
Now here's a skill that is trickier to master. It's deceptively simple but it took me a while to get the hang of it. Soul Harvest is, simply put, a buff. When activated, for each enemy in a 16 yard radius, up to 5 enemies maximum, you will gain 130 Intelligence. The buff expires in 30 seconds and has a 15 second cooldown. When I first used this, my mistake was that I didn't activate it when enemies were close. After I corrected my mistake, I learned to activate it correctly. The increase in Intelligence is significant. However, the 130 Intelligence per enemy applies at level 60. Currently at level 13 the buff gives "only" 36 Intelligence per enemy. If used correctly, this skill can improve your damage considerably. If you can make sure to always activate it when there are 5 or more enemies nearby, you can deal incredibly huge amounts of damage almost 100% of the time. The only time it might not be so useful is on bosses, assuming they don't have minions, but even then, a buff is a buff. To give an example, my level 13 Witch Doctor has 53 Intelligence and does 27.99 damage. When Soul Harvest is at the maximum 5 stacks, my Intelligence jumps to 233 and my damage more than doubles, to 60.93. That's... frigging amazing! Whatever my level 60 build will include, I'll be sure to save Soul Harvest a spot.
Lv 13 - Sacrifice
Sacrifice is a skill that works in concert with your Zombie Dogs. You can't use it on its own, because it detonates your Dogs for 200% weapon damage each, to enemies within 12 yards. This skill is somewhat similar to Diablo 2's Necromancer's Corpse Explosion. The problem is that you can't use it very often since Zombie Dogs are on a long 60 second cooldown. But there is a tactical aspect to Sacrifice. If you wait until your Dogs are almost dead, that's the best time to detonate them, especially if they are off cooldown. The skill effect is quite impressive, I'll give you that, but I haven't had much use for it in the beta. I'm waiting to test it more extensively in the full game, but right now you need to dedicate 2 (out of 4) precious keys to Sacrifice + Zombie Dogs and that's simply not worth it.
Passive Skills (1st slot unlocked at level 10)
At level 10 the first 2 passive skills are unlocked.
Lv 10 - Circle of Life
Here's a potentially interesting passive skill. For each monster that dies within 12 yards, you get a 5% chance that a Zombie Dog will spawn. You can increase that range by wearing items which increase your gold pickup range. Now, the first problem with this passive is that it doesn't seem to work if you are already using Zombie Dogs. If you thought that you would get an army of Zombie Dogs in short order, think again. This works bets if you don't normally use Zombie Dogs but would like to have some minions, nonetheless. The second problem is that the number of Dogs that spawn is same as the number of Dogs you can summon with your Zombie Dogs spell, namely 3, or 4 if you enhance this with a later passive skill. Third issue is that the summoned Dogs are the basic, non-rune-enhanced variety. For these reasons, I don't see this passive as being very useful, at least not at these low levels.
Lv 10 - Jungle Fortitude
Instead of Circle of Life, at level 10 I would pick Jungle Fortitude. The effect is simple: 20% less damage from all sources for you and your minions. Though it doesn't make much of a difference in the beta, it does allow you to play more recklessly if that's what you want. I bet that this passive will be invaluable for hardcore characters, in Inferno and PvP.
Lv 13 - Spiritual Attunement
At level 13 Witch Doctors get the most useful passive skill in the beta, one that not only increases their Mana pool by 20% but also increases the regeneration rate by an extra 1% of maximum Mana each second. I would pick this over Jungle Fortitude any day, especially since there isn't much danger in the beta, whereas there are some very Mana-intensive spells that can benefit from this.
Next, I will talk about my level progression from 1-13.
Poison Dart is all you get in your first slot. Use it to kill stuff.
Your second skill slot (right mouse button by default) is unlocked, as well as Grasp of the Dead, one of the most awesome Witch Doctor skills in the beta (and possibly the game)! For best effect, use it at range on groups of monsters. You will love it when you see how their health bars are depleted. Make sure to equip the best weapon possible (with the best DPS) which will improve the damage of Grasp of the Dead (as well as most other skills). Since Grasp of the Dead is an AoE DoT, it will be very effective in killing or seriously damaging large groups of monsters. Just be aware of its 8 second cooldown. You can also use it defensively, by placing it on advancing groups of monsters, which will slow them down enough for you to hit them with other spells. Since the duration of the DoT is the same as the spell's cooldown, you can chain this as long as you need to, whenever it's off cooldown.
Corpse Spiders becomes available as a primary skill. I suggest hanging on to Poison Dart, as Corpse Spiders is sluggish without a rune. You get more control with Poison Dart. But that's purely my personal preference.
Your third skill slot ("1" key) becomes available, as well as Zombie Dogs. There's absolutely no reason not to use it. Always keep your Zombie Dogs up, and re-summon if they die and the skill is off cooldown. Zombie Dogs can be very effective decoys. I wouldn't call them tanks because they will die from a powerful boss or when there are scores of enemies attacking them, but they play a very good role: that of meat shield. The Witch Doctor is, in my opinion, a ranged class and needs to keep its distance from monsters. Zombie Dogs will distract those enemies (although their damage is low) enough for the Witch Doctor to do her (black) magic.
Firebats becomes available as your secondary skill. You can choose to replace Grasp of the Dead with this but I preferred not to. The reason is that Firebats, although an awesome spell, will deplete your Mana very quickly and it has a rather short range, requiring you to get close to the action. In contrast, Grasp of the Dead feels free to cast and can be cast at the edges of the screen, before monsters can even detect you.
The first rune becomes available, namely Splinters which enhances Poison Dart. Equip it and you will notice a marked improvement, if you are still using Poison Dart at this point.
A second rune is unlocked. Groping Eels enhances Grasp of the Dead and gives it an extra bit of oomph (damage), which makes that skill even better. If you liked Grasp of the Dead before, you'll like it even more now.
You get your second defensive skill, Horrify. I don't see any reason to use it over Zombie Dogs.
Level 9 unlocks your fourth skill slot ("2" key) and also gives you a new skill to put in that slot, Soul Harvest. As discussed above, Soul Harvest has amazing potential, provided it is used correctly and refreshed accordingly. I would strongly advise using it. The only thing you will have to keep in mind is that you need to be more pro-active and to consider each move in advance. It would be a waste to use this skill when there are no monsters nearby or when there are only 1-2 of them, because then you'll have to wait for the cooldown before you can use it again. But if you can hit 5 monsters with it, you can double your damage for the next 30 seconds.
The Leaping Spiders rune is also unlocked at this level and if you haven't used Corpse Spiders until now, I suggest you give it a try. This rune makes that skill worthwhile.
At level 10 your first two passive skills become available. I picked Jungle Fortitude, for the reasons outlined above.
Plague of Toads becomes available as your primary skill. Personally this one didn't work very well for me so I chose to stick with Poison Dart.
The Dire Bats rune is unlocked for your Firebats and it transforms that skill a lot. I suggest at least trying it, if not outright adopting it, going forward.
Haunt is a new secondary skill that I highly suggest trying. If you like working with DoTs, this is the skill for you. One of my builds uses it.
The Rabid Dogs rune is now available for your Zombie Dogs. It gives them extra damage so there's no reason not to equip it if you like running with minions.
The third passive skill is unlocked. Spiritual Attunement is better than the other passives, at least in the beta, because it increases your Mana pool as well as the regeneration rate so you can use more costly spells.
Poison Dart gets its second rune, Numbing Dart. I ignored this one completely because it's irrelevant in the beta.
Finally, a new skill, Sacrifice is now available. As discussed above, this works in tandem with Zombie Dogs but none of my builds use it.
This concludes my discussions of the Witch Doctor's skills in the beta. I have used two different builds with great success but you should know that the Witch Doctor was the only class where I turned on Elective Mode for both builds, so I could arrange my skills the way I wanted them. I found that the game was too limiting in the way skills are assigned to each key. So here are my two level 13 builds:
Build 1 - This build features:
Poison Dart (runed with Splinters) on left mouse
Firebats (runed with Dire Bats) on right mouse
Grasp of the Dead (runed with Groping Eels) on key "1"
Corpse Spiders (runed with Leaping Spiders) on key "2"
Poison Dart is for cleaning up or smashing objects. Firebats provides the Mana-intensive nuke. Grasp of the Dead provides the AoE. Corpse Spiders is for massive spamming.
Build 2 - This build features:
Firebats (runed with Dire Bats) on left mouse
Haunt on right mouse
Grasp of the Dead (runed with Groping Eels) on key "1"
Soul Harvest on key "2"
Firebats provides the Mana-intensive nuke and is also used to smash objects (yeah, it's Mana-intensive but there's no other choice in this build). Haunt provides the powerful fire-and-forget DoT. Grasp of the Dead provides the AoE. Soul Harvest is the massive damage buff.
Both of these builds are a lot of fun. Lately I've been running with the second build because it feels even more fun, with the caveat that it burns through your mana a lot faster, with Firebats and Haunt which are both costly to use.
The Witch Doctor is a very versatile and fun class. It plays sufficiently different than all the other classes in both Diablo 3 and 2 to make it feel like a brand new concept. At several points during my beta career I almost made up my mind to make it my main in the full game. Eventually, I decided I would go the "safe" route, with the Demon Hunter, but I will definitely level a Witch Doctor to 60 shortly after my Demon Hunter.
The Beta Demon Hunter
The beta Monk
The beta Wizard
The beta Barbarian