Astounding

I've got to say, amazing work. I've seen quite a few flash videos around this place in my short membership, and this is amongst the best. The music, for one, sets the mood perfectly. I just love it.
The animation is lovely, as well.
Can't wait for the sequel, it's gonna be hard to top this one.

Decent

Wasn't special or anything, but it's decent enough. Got bored by the third weapon upgrade, but kept going until the plane boss, just to give it a chance. Great concept, and a wonderful try, but it's just too simple and linear for my tastes.

\m/-__-\m/

Respect, man. This would make amazing background music for a game. I should know, I've been listening to a lot of background music lately. Though I have to disagree with Chimy on it being in 300-type game. Just wouldn't work. I imagine it in a type of...RPG final boss music. Y'know, ever listen to some epic Final Fantasy music? Yeah, something along the lines of that.
Good job, you should make some more.

Amazing

Jimi, one of the best guitarists in the history of rock. I love it, beyond belief. Amazing work.