Walk Cycle: Remember, Feet don't slide. They lift by bending, straighten out forward, and come back to the ground before falling behind as the other leg does the same. Also, the body moves during walk cycles; When one leg is perpendicular to the ground, the body rises, and when the legs are farthest apart, the body falls. Arms also swing in opposition to the corresponding leg.
As for the sprite itself, do you really want the chest to be that big? I mean, I guess it's part of the character design, but it really looks cumbersome. Also, the leg hilight could be a bit more thick than 1px, as well as the one on the arm and near shoulder...but not by too much.
Mmm...seems like alot of platform spriters seek their legs from oldskool megaman...
Not a bad thing, but there are much more fasionable (and more easily animated) legs out there. But I guess that's a character design as well, as it fits with the bigness of the rest of the character.
The colors could use some desaturation and variation as well.
Is his far arm going to be holding a weapon?