This is just my opinion, so don't take it to fact.
Anyway, I have not beaten the entire game yet so I can't speak from all experience but I am currently on act 3 Inferno: Heart of Sin quest. I run with: ~450 resist all, with 1 resist at 520 and one at 600, 2800 armor, 36k HP, 35k dps and 2.2attacks/sec. I use splinters, rain of toads, GotD, Zombie Wall, Horrify and Spirit Walk as my skills.
It takes a very long time to down mobs just kiting them around (compared to other 2 ranged classes). My most damaging spell (Zombie Bears) I can't use because if I get close enough to mobs I will die and kiting with it still requires being somewhat close so it is risky. Dire Bats doesn't really compare in damage to bears and is very mana costly, can't see using it without VQ. Our CC spells (GotD, Zombie Wall, Hex, Fear, Confusion, etc...) have reduced duration on elites it seems and the options I feel I am left with is only splinters which is a forced kiting build that takes to long to down mobs.
Anyway, do you guys feel we are underpowered compared to the other 4 classes. DHs blow us up in dps as do wizards. Monks and barbs are melee so they are usually forced to be tanky but they can atleast sustain themselves to take hits while they kill the mob. I feel we are forced to very specific builds unless we have ~100mil to buy the gear we need to be able to run a high dps build and stay alive, not saying other classes don't rely on gear but I think we do more so then others. We are the only class that uses our resource(mana) to attack with our primary skills(dart,toads,spiders,firebomb) and since most of us use "Pierce the Veil" lets not forget to tack another 30% to our mana costs. I do think we have good CC spells compared to other classes but that is all that seems better. Our damage is lackluster, our pets aren't even the best (monk pet better), and we seen to be the most "squishy"/death-prone.
What do you think?