The music is great and the gameplay is really interesting, I like how when you get hit you gain a wider area!
I didn't like how the bullets were shot randomly (as far as I've seen), I think it would have been great to have some patterns that repeat (even if the sequence may be randomized to some extent, I'm thinking of Super Hexagon) so that learning the patterns rewards the player.
Anyways I was just impressed by the presentation, very nice game!