It's bad at it's job. It's legendary for it's numerous failures, often preventing people from accessing their paid for games. Before this version, I had the same problem with AC II. Was not worth finishing the game.
It's trying to do the Steam or Origin bit. Difference is, they hide it better. Steam actually has a properly functional store, and social service. So does Origin (Which has improved greatly over time, but still has some major issues, particularly with integration in core EA titles). uPlay is another piece of shit installed on my machine to check that I'm allowed to play the game I've bought, that I wouldn't use for anything else. Steam and Origin are already a penalty on a player. Imagine the player who doesn't have one of these services buying a game with it. That's the position HL2 put everyone in, with quite a backlash. That's the same mistake EA made with Origin, which got them a bigger backlash. And that's the same thing that uPlay is doing, because the user almost certainly does not want, need, or have any use for uPlay, and it takes time, installing, space, updating, and system memory to run. uPlay offers the player no tangible benefit. This is why, for instance, Origin has been releasing games for free. It builds up a player's library, builds loyalty, and gives them a reason to want the service, which serves EA doubly, to sell stuff, and to protect (sort of) stuff.