Framerate and Vsync problems spoil the game.
The problem with this game that firstly the graphics are not as nice as they looked on the publicity pics released prior to the game. To be honest it isn't that much better than than MotoGP 3 on the Xbox. Sure it looks nice when running at 720p but overall the level of graphical detail at most of the tracks is a bit dissapointing. There are also problems with erratic framerates and Vsync issues which cause screen tearing.
These problems are starting to get a bit unforgivable now. I could forgive some of the early 360 releases, but the console has been out over 6 months now, surely games devs should be getting better at coding for the 360 by now. I think the development team should have put the release back by 3 - 6 months and worked on optimising the framerate and looked at enabling Vsync to remove the screen tearing.
The game itself is fun to play although not that different from MotoGP3. It's just a shame that the technical issues let the game down so much. The handling is nice, there are plenty of unlockables, online seems fun although this also has its fair share of technical issues.
If you have never played any of the MotoGP games then it is worth a rental and maybe even a purchase. For those dedicated fans who already have MotoGP3 I would leave this one on the shelf and wait for next years release. Hopefully they release one with more content and which runs much better on the 360 hardware.