I made some predictions for Diablo 3. Looking at high end spells I figured that people would end up with health pools in the 50k range and I think by the time I get to act 4 of Inferno difficulty that will be true - I am at 40k now and I desperately need more HP. In theory I was going to play my Witch Doctor by hiding behind minions and raining down death on the enemies but in practice the Zombie Dogs are useless because they die instantly and even my single big Gargantuan Zombie isn't very tough. I need huge amounts of health, just as much or moreso than a melee character. My Int is about 1.1k, vastly off from my guess of 5k, though again I will likely end up a fair bit higher before I beat the game.
The thing I got really, really wrong was Magic Find. I am very glad to be wrong. MF in D2 on any decently geared character was in the 300+ range and Blizzard implemented a harsh diminishing returns formula to curb it. Given that MF was present at level 1 in amounts of 5% and so were other stats I assumed people would have thousands of MF. Instead MF scaled from 5% at level 1 to 10% at level 60. Top end gear that has MF only has 8-16% and the monsters are savagely powerful so you can't possibly stack MF and ignore other stats if you want any hope at winning. This setup works very well I think; MF is a fine thing to have on a piece of gear but the numbers are small enough that it needs no diminishing returns. Some people value MF heavily of course, and some don't, but I am sure you will see top end characters with 0% MF on gear and other ones with 80% and both will be reasonable.
The build I ended up settling into is extremely close to the one I built just based on beta knowledge. The fundamentals are the same: Abuse Vision Quest to generate massive amounts of mana and Soul Harvest to generate massive amounts of damage. Here is the thing about Witch Doctors that is utterly bizarre:
Cheap Spell: 4 mana.
Expensive Spell: 30 mana.
Mana Pool: 100
Mana Regen: 20/sec
Cheap Spell: 10 mana.
Expensive Spell: 140 mana.
Mana Pool: 700
Mana Regen: 20/sec
As you progress from level 1 to 60 you go from casting an expensive spell every 2 seconds to casting one every 15 seconds. There are things you can do to up your mana regeneration but none of them mitigate the pain of levelling up enough. Other classes do not work this way as they all have fixed resource pool sizes. Vision Quest increases all mana regeneration by 300% as long as you have 4 abilities on cooldown so you have two build choices: First, to use a normal build with a cheap spell and cast expensive spells rarely. The other option is to use 5 cooldowns and 1 spammable expensive attack and leverage Vision Quest. Since you need every defensive cooldown you can get in Inferno difficulty it isn't hard at all to find 5 cooldowns you want to use.
It turns out there is a fantastic spell to be your only attack spell: Zombie bears. In addition to the awesomeness of hurling rotting bear carcasses as your attack the actual in game mechanics are fantastic. Each cast creates 3 bears that appear behind you to your left, right and centre and they rush a decent distance forward. They do utterly stupendous damage and hit enemies on all sides of you as well as ahead and behind. Nothing demolishes a crowd like a WD casting Zombie Bears because they hit incredibly hard even for a expensive spell and nobody else gets to spam expensive spells all day long.
The critical issue is that against large enemies all 3 bears can hit. When there is a stationary boss I can easily clock in 100k dps when other classes with my gear would be struggling to go above 25k. It makes the game fairly unbalanced when 1 class can do 4 times as much damage as another even if there is a cost associated. The cost is fairly high since my Zombie Bear build has no long range attack so against a boss like Izual I simply cannot win since I cannot fight at range and I cannot live when nearby. I don't think it is an especially good balancing factor to have WD be utterly ridiculous at many situations and useless at others particularly since I can respec if I have to.
I think the WD mana model is a bad one. There shouldn't be one passive ability that completely defines the class and causes huge balance issues with every expensive spell. The best way to fix this would be to ramp up baseline WD mana regeneration at higher levels so that expensive spells are reasonably castable and nerf or change Vision Quest. Zombie bears are very powerful but would be plenty balanced if their cost was a real mitigating factor. When you can ignore their cost things get completely out of hand.