Fun game, just got done playing the demo.
The combat is a little stiff, it is fun, enjoyable, not frustrating in the least, but still a little stiffer than it could be(this is an ultimate "that's what she said" line, btw).
The ground game is hard to say. I was able to easily get side-control, mount, etc, etc, as well as defending postions and standing up. The problem is the NPC you are fighting sucks ass and you really have no clue how good it is going to be when you compete for positions against a real player.
Shogun's clinch is awesome, the muay thai clinch. It's fun, easy to control(against the bad NPC). You can pull his head down and side to side, throwing knees at the right time.
Striking in general is fun as well, you have all the high kicks, body kicks, leg kicks, knees, dirty boxing, etc, as well as the hooks, counters, straights, super-man punch, overhand right, spinning back kick, etc.
All in all, it is a fun game with a bad NPC so you can't tell how competitive the ground game will be.