The big new features are the Composure Meter and the Impact Moment. The former keeps tabs on how all of your players are "holding it together." Drain a three and watch the shooter's composure rise. Or take a charge on defense and get another boost. Alternatively, if you're on the road and the home team goes on a run, your whole team might suffer, necessitating a timeout to regain some composure. Make enough big plays and you'll trigger an Impact Moment, in which you can dance with your team's cheerleaders, tease the mascot, play to the crowd, pump up your teammates or even get in the faces of your opponents, lowering their composure.
Whether or not the next-gen debut of March Madness makes the grade is not yet known. Last year's Xbox version introduced great ideas (like the Lockdown Stick) that were poorly implemented. The 360 iteration is certainly talking a great game, though, so here's hoping it backs it up on the court.