I got one of the pieces of music today and its great - it really gives the game its feeling and atmosphere. In fact the exact same thing happened with Maul Ball. It was an okay game before the music, perfectly servicably but nothing special. But when the music was added it became fun. I'm fully convinced that music is one of the most important pieces of the game's feel - without it it just lacks substance.
In other news I downloaded the Gish demo - what a game, the physics are just so enjoyable to mess with. It really shows what two guys can do.