Whoa! Easy there...My main reason for tossing $10 for this game is cos i got a couple hundred songs worth "Riding." I've got alot of songs to ride.
The whole concept is at their website audioSurf.com
From what i've seen they take the rythem, beat, vocals, etc and use it to form the bumps, curves, and twists(and more) of that track...you can pick from a set of characters...each one has a vehicle, using either the keyboard, or mouse, you can move your vehicle left or right and perform special features of that character.
If that's not your cup of tea...that's cool. I just found the concept interesting, gave it a shot and got my money's worth.
Though i'm told some of the best rides occur when playing "The Doors." As seen on youtube some of "The Who" videos are intense rides.