Graphically above average, nice music, decent gameplay. The controls feel unresponsive sometimes... and I would have liked to see more variation on the established theme.
Solid game.
For all of it's shortcomings, it's still a lot of fun to play (and replay).
I sort of dislike the way the flying creeps are spread out. This rules out a lot of strategies.. maybe you could make levels without this. A way to speed up the pace would be good as well.