I'm of the camp that even if it worked well, ACU is not a very good game. It's alarmingly blatant with its amount of dull collectibles, stuffed with tons of side missions/activities that are as bland as 'go to thing kill guys go to other thing' done. I don't mean like on its basis, I mean that's the whole side mission. With about two sentences of dialogue. I find that it actually controls worse than the previous entries whenever you're trying to climb up a building with a lot of geometry, and the combat is SO clunky. Clunkier than any of the previous entries. The original ACs combat was clunky, but they made it so easy that you can force your way through it. Now you can't force your way through it, so you spend even more time noticing how bad it is. It's also information overload when you get to spots like the Cafe. Where a game like GTA would let you explore and figure out the minor things out, Ubisoft demands you know every god damn little 'new' mechanic they stuffed into the game.
The only thing the game has going for it are the two main characters and the setting. Oh and the descend button.