Good, but seen better.
The fact you can select your whole outfit from the helmet to the boots is a good addition to the game. I also like that they used big brand names like Ducati, Yamaha, Suzuki, Honda etc. They also used bikes I had never Heard of(Triumph) so that is good. There is also a variety of tracks so the scenery is different in each track. You also have to unlock the better looking bikes (that are also the faster ones). That makes you want to play more.
The thing that frustrated me the most was the fact that it is easy to crash and the fact that your opponents always get in the way when trying to pass or they get in front of you when on a straight. You need alot of patience. You will have to restart.
So to sum up if you like to see someone fall off a bike, or you have a very big patience capacity or if you just plain love bikes get this game, but if not I would recommend MotoGP 3 or MotoGP07.