A very poor port of a decent game
Assassin's Creed 2 was a very poor port. There were many odd lags in gameplay. I would reach an objective, and then have to wait for the game to realize I was there, and load the next part of the story.
This caused confusion and a failed mission on one occasion, because I beat up a guy—which was the objective—before the game specifically told me to.
There is no controller support. And even other options like joystick mapper don't work, because the game doesn't recognize the input. The on-screen prompts are horrible, because instead of telling you to press a certain key or mouse button, they indicate a colored circle that you are supposed to have figured out which key is mapped to it.
Add to this Ubisoft's requirement of a constant internet connection to play (and their buggy server that didn't recognize my internet connection for weeks), and you have an allround crappy port of what seemed like an otherwise interesting game.
Ubisoft needs to outsource their porting to companies that can do it right, like Feral or Aspyr.