On the outset, there aren't many changes compared to FIFA 09 which was already a very good game. This is good because the subtle changes introduced to FIFA 10 have basically rectified the minor weaknesses of the previous version.
The gameplay is very smooth now and very realistic. It is fun to play. There aren't any particular formulae to scoring goals. Scoring on corners is much more tougher.
It's an excellent game indeed. The crosses is where I have seen the best improvement with the balls curling in properly if you use the right players. That's another point. The skill levels of players really matter more now. What I can do with Kaka or Ronaldinho is not possible with Gattuso!
IMO wholesale changes were not needed so EA has played it right. The introduction of weather conditions is much better this time with snow, rain and various conditions in addition to night games for locations where we previously had dusk only.
My only minor complaint is that the game doesn't give enough time for celebrations! This was fun in the previous game but you have to be quick here or the guy runs into the net like a clown!

Still, this is a small thing and not part of the gameplay so I have to give it an outstanding rating.
Top notch game!

IMO, it's by far the best in the series.