A very nice game! Nothing revolutionary, but your first game doesn't need to be. I really liked the fact that there is actually a boss and an ending.
As for criticism: I would have liked it if the controls were a little snappier, the ships had a hard time actually dodging stuff. Also a menu with the controls could be nice, as I downloaded the game straight off the rate screen.
P.S. Playing a 2 player game alone is a little difficult :)