The concept of the game is pretty simple, but also fun and somewhat addicting. At first glance it looks like a futuristic racing game, but it's not. It's actually more of a puzzle oriented rhythm game in a genre of its own, the rhythm part might be a bit of an overstatement too as you could probably play it easily with no audio as well, songs are there just to generate the track and add the "feeling" to the gameplay.
It's best played on a 360 controller in my opinion with the rumble and more laid back experience. The leader boards add longevity as you fight over the domination of your favourite songs with every other Audiosurf player. Normally I'm not too excited about achievements in games, but I have to admit that in a game like Audiosurf they work quite well, and encourage you to play songs you propably wouldn't otherwise try out.
The graphics aren't that glamorous but the visual style works with this game type, and it also keeps it from becoming too demanding for a bit older machines. There are several game modes divided into 3 difficulty levels to keep you interested for a while, most of them are easy to learn and good for a relaxed experience, but others which are more demanding and hard to master will also enable higher scores, if you know what you're doing.
I definitely recommend Audiosurf for every music lover out there, to me personally it's just a new way of listening to my MP3s, and it's as relaxing or intense as I want it to be. Leader boards and different game modes provide challenge, but how long the game can keep you interested probably depends on your own music collection. I can see myself coming back to it every time I get some new tracks to play with. For 10 bucks it's an offer you shouldn't refuse.