Ehh, not the best that I have seen.
But since this was your first time using sprites, it was allright. The flash was just too slow and the movements of the Metal Slug characters were just to slow and fast at different times. The music in this flash was pretty good though. I loved the Techno! Overall, you can do better and I will see your other Episodes sometime soon. This flash could be better.
-$eamonky