Well, Gamestop didn't get the game until 9:00 PM last night, so I only got to play for an hour or so (NCAA 2005). Gameplay is pretty much the same, although the new twists added are:
Matchup Analyzer: When you get up to the LOS, you can check the matchups to look for mis-matches (slow LBs vs. your stud RB, etc.). I only played one game, and against a crappy team, so I consistently got the good match ups. Can't see how this will help yet. Maybe when I play vs. a tough team there will be some insight.
Formation switch: Like in the last Madden, you can now flip your chosen play at the LOS (Thank GOD!).
Running and passing games seem a bit easier to control, and the pass defense for me was outstanding. Only a couple of "yeah, right" plays from the CPU (including the only TD the CPU scored--they threw to a WR in double coverage, and the QB dropped it over my leaping CB). Although my #1 WR dropped 3 easy passes in a row, which floored me.
And it appears that if you make a "user catch" or "user tackle" or "user interception", etc., you get more "Challenge Points" than before. In other words, you don't let the CPU catch it and then it switches to you, you actually switch to the WR after you throw the ball and you catch it.
Also, for those who love playing with the historical teams, you can finally EDIT THE HISTORICAL TEAM ROSTERS! Woo hoo! The classic games are all back (with no new ones added, unfortunately--you would think they'd add the BCS Championship Game, Ohio State vs. NC State, Miami vs. UT, etc. from last year), the Mascot teams (yawn), and SI in dynasty mode is still there. Haven't started a new dynasty yet, but I also read that there are other things to think about now during the off-season, mainly to do with keeping you players happy.