I'm a bit of an MMA wonk (Though I haven't been able to train in a little over two months -- Stupid foot is STILL kinda jacked up).
I was somewhere between interested and deeply concerned to find that they were coming out with another UFC game. MMA games have traditionally sucked in a big way (Of particular amusement was the ease with which you could KO some dude who had mount on you).
Amazingly enough, they pretty much got it right. There's a good bit I could complain about, but it's a very solid effort by THQ. For the offline people, the career mode is excellent (I recently got my arse handed to me by Mike Swick).
Submissions are a bit out of balance, almost impossible to pull one off. Flash KOs are a -bit- too frequent compared to TKO/ref stoppage. Controls are pretty complex, but it's a very deep system so that makes it quite worth it to me.
A good start to the franchise.