Art: I dig it.
Controls: decent, although the cannon aiming was a bit frustrating since the bullet was so small. I kept thinking that I had a really accurate shot, only to miss by a couple pixels resulting in a crashed ship.
Overall mechanics: Good, although I think there may be a bit more potential in there.
The first few levels didn't give me a lot of optimism, but you won me over with the 2 ship tier. Fun stuff.