There are so many decent stick fights on Newgrounds that you really have to push yourself to stand out at all. Unfortunately, this one doesn't. On the upside, it gave me ideas. And you know what they say about ideas in Inception.
Anyway, the first thing I noticed was that your speed lines lacked any feeling of motion for some reason. Once, it felt like there was movement, but that was once.
Second thing I noticed was that the dust from the guy sliding along the ground didn't even look like it came from him sliding on the ground. I'd suggest showing the guy fly a little ways, hit the ground, then cue the dust, so the viewer can see that the dust wasn't there to begin with.
I feel like the special effects come and go too fast. They have almost no impact, it seems, and no significance. I'm not quite sure how to explain why I didn't like them. I think that's the best I can do. No impact. Too fast. Insignificant.
The music gets going and the battle ends. Generally, don't you want your music to match the length of your movie so the climaxes are simultaneous, therefore providing a more compete feel to the animation as a whole?
Finally, the credits. Having your name be the only one under every category could be funny if done right, but it goes on too long. If the credits were 5 seconds, I'd like them more. As it is, you could just write "Everything" and then your name.