I actually had a lot less issues with UFC 2010 than most. I thought the sub system needed tweeking but not massively.
The 2 main things i have issues with from the last game is that you hardly ever got TKO wins. 90% of the time you'd get a flash KO when in reality most fights in the UFC end by TKO, i'd liek to see a gradual wearing down of your opponent and as opposed to just big one punch KOs.
Also the judges scoring on the game was crazy! I'd have a pretty even fight where i felt that i had the better of every round and i'd end up winning 30-23 across the board, Which is just unrealistic and puts you off going to decision.