Not before I've beaten Parappa The Rapper, which looks pretty short though. (Don't go telling me there are better and more modern rhythm games, I know. It's just that I've been wanting to play it since its Playstation times, which makes it eleven years straight.)
I've read an interview to the developers of Patapon somewhere, and it does look very promising even just from the concept. I didn't figure out that gameplay would influence the story though.