One of the more disappointing FIFA in modern years. EA continues to focus on "features" rather than gameplay.
Unfortunately, this often causes the actually football to play second fiddle in the game. As a long time FIFA player (all the way back to '95), I feel informed enough to say that this is one of the most disappointing games I've seen EA slap together. I'll hit a few main points that have most stood out to me.
I'll begin with probably the only positive I can think of, and that is AI player movement. In short, its absolutely fantastic. Both teammates and opposition sprint around the pitch in brilliant runs to space, decoy runs, and defensive zone marking when faced against a breakaway.
Another mildly successful reform is shooting, which FIFA continues to make more and more challenging. I find that the shooting to be more life-like and accurate.
One of the most frustrating aspects is the referee who is inconsistent at best. If you so much as kick dirt on a player from any direction besides a head on slide tackle, its a booking. However, the head-on tackles don't have to be precisely timed. I often absolutely flatten a player with a slide tackle several seconds after the ball is gone and not even a foul is given. In my opinion, '08 was the best referee (besides the fact that he could not go back after play was over and give cards) and there was no need for EA to meddle with it.
Another problem with slide tackling is that it takes a defender so long to get up from it, the attacker can often retrieve the ball and run on uncontested from perfectly timed challenges. I've all but abandoned slide tackling.
Finally, I'll look at ball winning from standing challenges. Clumsy is the best word that comes to mind. If you come anywhere near a defenders "zone of influence", you will lose the ball regardless the match up. I know the shielding in previous games was a bit ridiculous, but this new system is honestly worse.
All in all, I'd advise to waiting this year out and keep playing '08 and '09 till EA gets their stuff in order.
PS: As an afterthought, I'll throw some praise towards goalkeeper mechanics in '10.