I dunno if it's even really a matter of balance that makes me dislike it...
The controls are really wonky on it, you can't shoot downward at someone from a window without taking cover. Never noticed anything like this in single player, maybe just because it's played a lot differently.
Everyone's names show up above their heads, meaning everyone knows where you are if you are anywhere on their screen. This is kind of necessary to cut down on campers because otherwise everyone would be hiding in cover, but still ruins it.
And honestly I think it might just be hard to make a good 3PS multiplayer game. Also hard to make a good multiplayer game that has a cover system, because cover systems are fucking stupid. Seriously the disadvantage of being covered from all the bullets should be that you can't see, such a terrible thing to put in a multiplayer game.
I'll give it another shot but right now it seems pretty mediocre to me. Especially compared to the awesome single player.