Not too shabby. All of the sprite animations were very smooth and the working of camera angles and so on worked out well throughout the entire flash.
And like you said, the idea isn't very original either since it has been done a million times before, but it was for a competition, so you were quite restricted to pan outside of that.
I think you might actually have something extraordinary if you could piece together a work that had more than just sprites fighting each other for the remainder of the movie, which seems to be all you have done so far, so hopefully your next piece of work will feature some kind of a storyline or plot to it. And maybe not get stuck with just Mario and Sonic type sprites, and maybe edit some sprites yourself to really give a full spectrum of what you're capable of.
Other than that, everything was pretty good.