fun
but it's a little too easy. doesn't really require any skill, and there's only one difficulty setting. played through once and unlocked everything, which doesn't allow for a sense of advancement.
one thing i do particularly enjoy, though, is the HP system--losing HP when you fire, and gaining it by collecting pixles. very nice, but it's too easy to stay alive.
and finally, i love the music. made me very happy inside.