The career mode, which really is what I played 2009 for, is
vastly improved. To start with, and perhaps the biggest change, you're no longer restricted to one of Kickboxing, Muay Thai and boxing on stand-up, and one of Jiu-Jitsu, Judo and Wrestling on grappling. You can pick and choose any move in the entire game. Okay, not the entire game, a few moves will be specific to real UFC fighters, but most will be available. You can learn new moves (in one of three different "levels"), by going to camps and learning them from fighters. They also added moves from Sambo and Karate this time around.
Then, once you actually get to start the game, the mode is expanded from 7 to 12 years. Now your fighter ages as well, and stats will decay if you don't keep an eye on them. Another of the additions that isn't technically
major, but adds a whole different world to the immersion, is that now you don't just start right in the UFC. You start out as an amateur, and when you think you're ready, you go pro. Then you get into the WFA (World Fighting Alliance, a small, not very good promotion that the UFC bought up a few years ago: Machida fought in it, among others). There you do well for a few fights, and you end up in the UFC. You can also be dropped back into the WFA if you can't cut it in the UFC.
Another of the immersion changes is that now you can have your fighter (which can have one of 5 different voices) say different stuff, like at weigh ins (respect/disrespect opponent), post fight interview (respect/disrespect/generic/props to the fans, that sort of thing), etc.
Another change that seems only cosmetic, but actually has an impact, is their ambitiously named "Game Watches You" system, where the game will react to what you're doing in fights (and out of fights, like if you disrespect a player from a certain camp, they might not want to teach you moves). Like if you're very fond of the high kick, the commentators will point that out, and your opponents might get closer, or try to take you in, things like that.
Can you tell I'm exited? Thing is, I really quite liked Undisputed 2009, and from playing the 2010 demo, and reading all the rave reviews on the Career mode, I'm ridiculously exited about playing the game. It just might reach fanboy levels when I actually get the game.
I implore you, if you like more realistic and complex fighting games, and if you like MMA in general, try it out. If you liked 2009, or thought it could have potential, you
will love this.
I feel like THQ should be paying me something for this, or something 
" moments. Like the flash knockouts that are still there, even on the demo. The ground game against the AI is completely retarded. The AI doesn't seem to care about the character's stats. Subs are still shit. Then there's those minor things that really annoy, like Machida's takedowns being completely unstoppable. You just know the full game is going to be plagued by these little indiscrepancies. I might still get it, but I'll most likely wait for EA MMA that comes out later this year