I've had it for a while. It's decently cool, and definitely worth the minuscule asking price.
Also while we're talking about games that generate levels from your music, Beat Hazard and its excellent DLC/expansion Beat Hazard Ultra are 50% off during the summer sale. Whereas Audiosurf is a puzzle game, Beat Hazard is an arena shooter along the lines of Geometry Wars. Or Robotron for the oldies ^_~. It's my go-to chillout game.