If you love the sport and don't mind spending time learning the moves, you'll be well served with this game.
This is also a blast to play with someone who knows what he does as the end can come quickly, at any time and in a lot of different ways.
Of course this is not a game for the same market as Street fighters or Tekken. Super powers comes from mastering the game in it's many and intricate details. It helps if you follow the sport and know a bit how to roll.
If you just started liking/looking at MMA shows, this game can teach you quite a bit about the sport. Of course it's over simplified compared to the real sport but if you learn a couple of positions, transitions and submissions from the game, you'll end up enjoying MMA events even more. (everyone enjoys strikes)
Overall I think this year's Undisputed is a big step forward from 2009 in terms of presentation, gameplay, options,variety and immersion. The career mode is much more enjoyable than last year, the controls are tighter, the roster is bigger, there's a ton of real moves to chose from for you to make your perfect fighter. The pros are also acting a lot more like their real life counter-parts as they each have their own unique flavor.
Some gameplay flaws are still there which can be quite infuriating sometimes (like the infamous mount-to-side control-to-north south-to-side control-to-north south problem) but most of the time, when I lose, I can see why and come back stronger the next time.
If you're a fan of the UFC or any other MMA organization, you own a console and you are willing to pour a little effort in mastering the controls, I think you'll find this game extremely enjoyable just like me.