Dude. It's sick. The standup is 10x better than last year. The fighters look better. Pretty much everything is improved. THQ gets an A+ in terms of the game IMO.
Back mount is a huge addition.
Edit: The first CPU vs. CPU match I saw was sick. Machida was bleeding all over the place. Rashad picked him up and power slammed him and rocked him. Then he just postured up from side control and finished him off.
It's sad, but that had me really pumped.