Easily the better game of the two.
Some improvements now have made the game better, which includes graphics, animations and better pacing of the game. If you have played fifa08, u would find this title's gameplay similar to past year's but it won't stop you from playing it.
Graphics:
No framerate issues, no replaying lagging. Player's jerseys looks like the real thing. Players animations and facial features are better than ever.
If you're going to compare this with past year's series, you probably won't find a big step forward in the graphics department, but rather there's a lot more animations and less exggerated sweating of players. Other improvements includes the skies, stadium and crowds.
Gameplay:
It's better than PES, although some fans of PES would disagree with me. Playing fifa and then PES, it makes you wonder why u actually though PES was realistic during the PS2 age. The gameplay you get on fifa09 is realistic, simulating and enjoyable at the same time.
Tricks is something thats useful but hard to master. Most people wouldn't believe tricks does much to change the game, fact is: players like C.Ronaldo who is a master at tricks are acknowledged as the best player in the world currently. Tricks does magic, but you need to use it at the right time depending on your position.
Goalkeeper is a real improvement this year, they parry shots, block shots better than realife counterpart. Which comes a small complaint from me, the goalkeeper are too good, more often during 1on1 situations, your chances of scoring is very slim. Which makes you think that your work in getting pass the defenders are kind of wasted effords. Most probably the time you would score is when you hit the poles or you get a second shot when you GK parry the shots to you.
What differentiates fifa09 gameplay with PES gameplay is the tiny details fifa put in. Rather than robotic animations seen in PES, EA sports went to the trouble of motion-capturing to get that realistic animation you see. What results in is better flow of gameplay and animations are smooth and players act like humans rather than robots. Play PES and you find that every animation are robotic, shooting, sliding...
Putting in linesman and referees is a plus, althoght it's the first time you see referees or linesmans on the next-gen console, these AI controlled elements are very well done and polished. Despite all the improvements, i still felt that the core gameplay needed more improvements to last it for a year. Other may not felt so because i played fifa08 for a year already.
Sound:
Commentary sounds the same as last years, but they put in more lines, making it less stale. Again! when you compare PES's commentary with fifa, PES is a joke, robotic commentary again, in fifa09 at the least you get commentary lines like a small brief history of man u or chelsea.
The bad would be the gameplay modes, it's similar to last year's. Commentary doesn't have much changes. But the additions made is enough to cover up the bads in this game.
Overall, i would anticipate next year's fifa. But i would expect more changes to the already great gameplay and probably a brand new commentary lines. Fifa09 is probably the best soccer game to date, leading PES by miles.