This year's version is leaps and bounds ahead of last years incarnation.
First, the gameplay feels more organic as a whole. You actually have incomplete passes recorded after a receiver gets hit hands on the ball...only to have it knocked out by the corner or safety. Swats work effectively this year as well on pass defense. The line play is much better and the running animations/tackle animations are better than anything we have seen thus far on next gen consoles.
Second, the difficulty levels are much more in-line with the gamer this year. I have not tried AA, but, I just played on default Heisman Alabama (me) vs Ohio State (CPU) and won 31-18. I was able to run, passing was a challenge and I was extremely happy with the way my defense played. I allowed 252 total yards of offense, but, it felt like a lot more with Pryor scrambling. I also noticed a dramatic drop in the amount of 3rd down conversions that have seemed to plague the franchise and I was able to get penetration with my lineman and didn't have them falling all over the place. I was able to record 5 sacks in the game - only 1 of them was a user sack with Darrington Sentimore.
Very happy thus far with NCAA 12! Can't wait for updated/named rosters along with named coaches!