Well, I don't like how everyone sprints like they have to take a crap. But, mainly because I find it too distractingly humorous rather than actually hating it.
As for the rest of the stuff, nah, nothing I really hate. I can't even muster up any bile about multiplayer anymore, suffice to say that it's fun with a friend in short bursts.
But I have my expectations lowered, I was disappointed in Mass Effect 2, largely because I hyped it up so much and because I absolutely loooooooooved the first one. Seriously, I know I've likely said this hundreds of times before, but I love it, my absolute favorite game.
At any rate, I don't expect the third installment to top the first one in my eyes, so I really can't be disappointed by it.