this was a sprite for a fast paced action game, so i didnt really bother with details at the time, but thanks for the tips! if i find the time (the fact that i'm replying about a month late shows you how much time i have for revisiting old sprites and such) i'll make it smoother and better looking 
Movements were ok, you could try adding more shading and/or dhittering, and make the movementation less stiff too.
Is he kicking the air with one leg and then with the other while moonwalking? :) I'd suggest that when landing the legs on the ground, you place them at the same x position he has them when lifted up, otherwise it gives a weird feeling, as if he was kind of sliding backwards.
The character looks interesting, it kinda reminds me of those dark creatures in LoZ Twilight Princess.