Finally a football game that LOOKS 'Next Gen', now if only it would PLAY like it was 'Next Gen'...
Gameplay-wise, there are a lot of changes to go with the new look. The big feature is the Pro-Tak system, which allows for up to 9-man gang-tackling. This makes defense much more realistic to play, since quick defenses that are able to converge on the ball-carrier are actually effective in the way they are supposed to be. Another significant gameplay change is the reduced pace of the game. Plays are slowed down considerably since last year's game, making gameplay much more fluid and easy. Additionally, defensive linemen are finally able to tip passes at the line or as the QB is throwing, resulting in "lame duck" passes that fly up into the air and are a free-for-all. These are all "About Damn Time" features, but they are still not perfect. Gang tackling animations don't always happen when you expect them to, and a lot of them stop the momentum of all players involved completely. The deflected passes don't come along with any of the actual rules and AI that should go along with them. For example, offensive linemen don't do anything to try to catch the ball or stop defenders from catching it on deflected passes. They just stand underneath it. On top of that, if the ball does hit an offensive lineman, the game does not call the "Illegal Touching" penalty. Kinda lazy.
Some other gameplay and AI improvements include receivers and running backs doing a better job of staying in bounds after catching passes near the sideline, weather having a greater effect on play (receivers slipping, kickers not being able to kick as far, etc), controls are tighter and more responsive, defensive coverage assignments can be made from the pause menu, and fumbles now sometimes result in a pile-up-mini-game. But other issues remain. Blocking (especially pulling linemen and pass blocking) is still horrible at higher difficulties, AI teams are still overly-dependent on the passing game, clock glitches, offensive player motion glitches, human players can't audible out of Special Teams plays (but the AI can), and the AI automatically becomes unstoppable when trying to catch up (especially inside of two minutes of a half) and then never gets out of its "catch-up" mode.
Overall, Madden 10 is a MUCH better game than Madden 09, and a big step in the right direction. But the fact that EA rebuilt so much of the game from the ground up but still was unable or unwilling to address so many of the series' existing problems is both baffling and disheartening. The continued reliance on pre-canned, motion-captured animations still hinders gameplay, but more modifications and variety of these animations makes repetitive animations less noticeable, which is good, but I can't help but wonder what it would take for EA to actually drop the motion-captured animations and go for a truly "Next Gen" physics-based animation system that generates all animations on the fly.