Not a bad side-scrolling shooter.
I have a few complaints, though. The whole thing seemed to move kind of slow, the sound just didn't blow my skirt up, and some of the enemy ships were apparently indestructible. That was a bit frustrating. You may want to consider adding in some level distinction, with an accuracy report at the end of each level. Nevertheless, it's a nice game, and damned good to have been done in four weeks.