First the Good: You can actually slide tackle and not get called for a penalty! They focused much more on defense this year. You can steal the ball pretty easily in Fifa 11. It seems to be more difficult to score goals, and crossing still needs to be tweaked. I have yet to score a goal off a corner. I do like the player personalities this year and the focus on incorporating skill moves in the game.
The Bad: My first impression was that they blew it with Fifa 11 and ruined the game. What I've noticed is that they screwed up "Be a Pro". After really loving this mode in Fifa 10 and World Cup SA, its frustrating to watch your teammates ball hog and lose the ball in this years version. I gave up. The good news is that if you play the normal method where you control every player then its actually a good game.
If you erase any expectations from Fifa 10 or World Cup and look at it as a new game then I think you will be happy with it. The beauty of Fifa games is in their replay value, they never really get old.
If you have only played Fifa 10, then this will be a great improvement from last year's game. But if you have played Fifa : South Africa, you won't notice much difference in the gameplay. It's basically the physics of Fifa : World Cup with the game modes of Fifa 10. Good game overall, but not much of an upgrade over Fifa : World Cup.