This game is fantastic, a bit hard to get used to after playing a lot of car racing games, but now it is fantastic fun. With 20 bikes in the field, the racing is fast an furious, and you're pretty much always battling with atleast three other bikes. Four player multiplayer just makes it even better.
The graphics are stunning, you can see tyre treads on your wheels, skid marks left behind from previous laps, and even the drainage grill at the side of the track. The AI is not outstanding, but perfectly reasonable, the racing is by no means dull.
The audio is pretty cool, you can hear other bikes approaching you and tell what side they are on. One slightly odd thing is the engine note of your bike. As you move up the gears, the engine note gradually gets higher pitched with each gear. So as with a normal engine, the pitch increases with the revs, then you change up and it should drop back down, but it actually continues to rise from where it left off!
The custom rider feature is another welcome addition, and with two different Championship modes, time trials, single races and the excellent multiplayer mode, this game has it all.