This game is great, online needs something, lag kills it, career is too demanding (on expert)
Getting down to the Nitty Griddy, I've played 2009 extensively, and I've got to say, i like this one a lot better, but this should have been maybe a DLC? not a full on game, the thing i really hate about the UFC franchise (games) is that the online is such a sad attempt, if the lag was not so bad, i'd love it, but its kind of hard to fight anyone when you can hardly move.
Camps are a great idea, but here, they are broken, hard to maintain, and even harder to get people to join, but besides that, online is fine.
Another thing you might like is the new "sway" control, it helps if you are really good at predicting players, but they can also work against you, which always makes it fun when others find out how to use it, but lack the skills to use it efficiently.
I like how they changed up the knockouts, now you can knock out in almost any angle, for one, when someone was trying to shoot, i punched their head on my side and they were knocked out, great way to cover all sides of the battle.
Submissions... AHHH! i hate them, i have 85+10 submission defense/offense, and i always get submitted and i can never pull off any submissions, they are a tough egg to crack, but hopefully i can get better at it, its hard, but once you get a good grip on how to use them, you'll be great.
So for the game UFC Undisputed 2010, i think it deserves a 8.5 out of 10.