An upgrade from it's predecessor, but lack of new innovation keeps it from being great.
The fighting engine in UFC 2010 is similar in almost everyway to the engine of 2009, with a few minor tweaks. It still uses the main four buttons, one for each limb, and you throw either head or body aimed strikes. One new aspect to the game is you are able to sway in order to dodge punches. This is similar to the dodging in the Fight Night series. What is nice is that you can combo sways into more powerful punches. You can duck forward and then throw a looping right or left hand while your head is down. This makes the fighting feel a little bit more realistic because you can bob and weave your head manually.
There are a couple of new game modes inside UFC 2010 also. There is the classic create-a-fighter mode where your own fictional character climbs the ranks in any weight class. They added a mode where you choose a current professional and try to climb the ladder in each weight class. This is a great game mode for two reasons, 1. it gives you a real reason to use your favorite fighters for once and 2. you get to fight a lot of real fights with no training time between each, it's just fights. The classic fight mode is also back, where you have to reenact classic UFC fights and duplicate the result. This is very challenging, but rewarding when you finally beat a fight and unlock behind the scene videos about the real life fight.
The most challenging thing about this game is submissions. The computer is almost unrealistically good at them, and manually, it is extremely hard to submit the computer. When the computer gets you in an attempted submission, it's almost a guarantee that they will complete the submission. This is frustrating since it takes away many aspects of fighting. You'll find yourself not throwing anyone to the ground since you have to be more than careful not to get caught in a random submission. The risk of ground of pound is not even worth it sometimes.
Overall, UFC 2010 Undisputed is an entertaining sequel to its highly successful predecessor. If you liked 2009, then you'll like 2010. It will provide you with hours of play time and the online multiplayer, although extremely challenging, is fun. This 2010 installment has not added anything drastic, which keeps the game almost identical to 2009, but it's still worth the $60, especially if you're a UFC fan.