Are you confused? Amplitude (PS2) did not let you use your own music. It was the direct ancestor of Guitar Hero.
If you're thinking of Audiosurf, this really strikes me as a clone of that, powerups and all. However, the mapping of required actions to the music is much tighter and more direct, and of course each track is separated into a different lane. Audiosurf tends to relax me, whereas this one is extremely hectic. I think each has really compelling features, but I think this is better as a game.
IMO, this game is only worth the price if you have Rock Band 3 and significant quantities of DLC songs and would like to have more than a couple songs from the 25 songs it comes with. It's a lot of fun IF you have a huge Rock Band library, like I do. It would get incredibly boring extremely fast if you don't. (On top of that, you will not have enough coins for powerups without playing the same songs over and over again unless you have lots of DLC, which I pray they will fix in a patch. It's the single worst design decision I've seen in a game this year.) In practice, it's pretty much a reward for longtime Rock Band fans.
That said, if you haven't tried Rock Band 3, I'd highly recommend it, though the instruments are expensive these days.