This is, no lie, the only game I've played on my PS3 since I got it 2 months ago (Resistance didn't really do it for me, and what else is there?). Basically my PS3 is a $600 flow machine. Is it worth a $650 investment (extra controller for multi!)? I would have to say no. Is it worth $8 though? Its a steal at $8. At $5 its a must own.
Mind you, if you don't have an HDTV I think it'll be a lot less great. It is beautiful to look at, and the sound design is lovely as well. I agree that it contolls better than anything on the Wii, it becomes really intuitive. Its true there's not a lot of depth, but its the kind of game you experience rather than just "get to the final boss."