Holy mother of god, this looks amazing! I'm in love with your artwork. The visuals on this are excellent.
It also runs pretty smooth, didn't look like it was suffering any slowdown or anything, and it's not like my computer is all that great so I don't think you'll have to worry too much about performance.
There are just a couple of minor crits...
The 8-Dir movement looks a little wonky when turning all the way horizontal just to move up or down, but you did mention you were going to create animations for that, so it's probably a non-issue.
Other than that I found one bug and one mistake:
Bug:
<img src="http://i38.tinypic.com/2dbw5dx.jpg">
These tiles are disappearing when scrolling up/down the screen.
Mistake:
<img src="http://i33.tinypic.com/t4zg50.jpg">
Your smoke trails are being created on the wrong layer (I guess you fixed the missiles but forgot to do the smoke? )
I dunno, I don't really have much to say about this other than it looks awesome, awesome, awesome. I still think you should go with fullscreen if you're going to make your window so big, but that's a whole other thread (and yeah, since then I hooked my computer up to my HDTV so I can actually see everything).