It is amazing.
However...if you're going to dive into the experience, buy it on Xbox 360. The game itself has 58 songs, and we went through them all in one night on PS2. Go here for the entire set list.
BUT...if you have the game for 360, you can download three new songs each week. Yeah, you have to pay extra, but I think it's worth it when the same songs just don't cut it. On top of that, soon they'll be releasing whole albums you can download, starting with Who's Next by The Who, followed by Nevermind by Nirvana.
Pretty badass. Can't wait to buy it, the original set list just isn't cutting it.