Yeah, there are other threads about this game, but most of them are along the lines of "EA MMA sucks" followed by "yeah" by others.
After trying this thing out, there are ovbious flaws but one thing where it really shines compared to the ufc undisputed, is the way you strike your opponent. It's very fluid and natural just using the right analog stick versus pressing a few buttons. The response is great so far. The take downs though feel a lot less technical and easy to defend against at times (so long as the opponent is pressing x (on PS3) at the right moment. The take downs, and take down defense on Undisputed is superior imo. Can get challenging due to the rotation of the analog stick and such, but I prefer that honestly. Same with the submissions. In EA MMA, it's a lot more difficult to nail the submission (If you aren't use to it) and even trickier to get out of one.
MMA isn't as random as Undisputed when it comes to landing that good shot and really rocking your opponent. I remember rocking someone really bad early in the fight where as in MMa, you have to really work at it. I think it could boil donw to the controls and learning how to swing the punches just right.
The speed and flow of the MMA is a bit more realistic compared to Undisputed. A bit faster (depending on your players stamina guage of course).
But overall, MMA flows really well. Undisputed feels clunky by comparison. EA MMA control scheme is a lot better honestly.
The visuals are better as well in MMA. The character models aren't as glossy looking as the UFC Undisputed (Fighters, refs, pretty much everyone) is. Plus the UFC character models, like Rampage tend to look a bit off. in comparison to say Bobby Lashley or Fedor. The models in MMA tend to look more like the people they are modeled after. The simulation of the way the fighters sweat in MMA looks dope as well. As stated before, Undisputed teen to look like they have been covered with gloss beforehand.
I like the way the refs get involved in the action in Undisputed, whereas with MMA, the guy is no where to be found, especially when you are finishing the opponent off. You just hear "That's it" out of no where and the fight is over. Undisputed actually has the ref involved during the whole match (even breaking fighters up if there isn't enough action) like they are in real UFC matches. Also, during the end of a round, you don't have your corner man talking to you the way you do in Undisputed. Which is a shame. Didn't really mean anything, and most people skip it, but it's details like that where Undisputed shine.
That's just my first impression hands on. The game looks really solid and could seriously be a contender. Undisputed do have to work out some serious kinks mainly with the control scheme of things, and improve the responsiveness when the characters are interacting. You can see and feel that more in MMA, whereas in Undisputed, the players heads just bob back if you hit them in the face, or the body tends to jerk a bit when you are going for body blows etc..
Would probably do a full in depth one once the full game is released.