I'm level 15 and I feel like a lot of my spells are pretty much useless. My boyfriend plays a Wizard and when we're playing together he does almost all the damage, gets all the killing blows, while I'm still trying to set up my spells. I can't really figure out which combo of spells to take to do good damage.
Left Click: I switch between frogs and splinter. I've found spiders to be annoying and useless in act II (can I please just summon the spiders instead of throwing jars at people, really?). Splinter seems to do the most damage, and frogs is frustrating because I can't aim them and I have to get up close and personal to use it, the damage is unpredictable. Splinters however, is boring as hell (if I wanted to shoot projectiles, I would have chosen a demon hunter). My hope, is that firebomb is better and more fun to use, because right now I"m not really happy with any of the primary attacks. This tree may be a deal breaker for me.
Right Click: I keep hopping between groping eels and dire bats. Groping eels is pretty cool, I'm happy with this spell, very useful. Dire bats, while the damage is nice, again, hard to aim, damage is unpredictable (just like plague toads), and I seem to OOM really fast when using it. Haunt seems kinda useless right now with no runes, my boyfriend kills everything too fast for haunt to really do anything. My hope, just like firebomb, is that locust swarm will make things a little better, but since its a dot too, I doubt it.
Defensive: Zombie dogs are fun, but die way too fast, they need to have a much shorter cooldown on this. Horrify, again, unpredictable, its too hard to move into a pack of enemies without WASD movement to be able to make this spell useful. Spirit walk, uhmmm, ok, it looks cool, but haven't found a need for it, at all. Hex looks neat, haven't gotten it yet, but it doesn't really help in the damage arena.
Terror: Yeaaaaahhhhh....I get that soul harvest has the potential to be bad !@#, but just like horrify, without WASD movement its too hard to maximize its potential in a large pack of enemies, and the buff duration is pathetic making it almost tedious to use. Sacrifice, also seems useless with the super long cooldown of zombie dogs, and the damage doesn't seem that great. I hope mass confusion is decent.
Decay: Mmmm, zombie charger makes me so happy :). Haven't gotten the other 3 spells in this tree yet, but they all look awesome and I can't wait to use them. This tree is what drew me to Witch Doctor. I just wish the zombie walked a little further lol.
Voodoo: Also mmmmm :) haven't gotten any of these yet either, but again, this is another tree that drew me to Witch Doctor.
Anyway, I may switch it up and try out Barbarian or Monk or something. Witch Doctor looked really cool but I'm feeling very sub-par at the moment, especially while grouped with a Wizard.
TLDR: Will Witch Doctor get more damage as I gain more abilities, because I'm not happy with his primary attacks and a lot of the attacks in some of the trees seem very situational and/or useless.