Where is the lightsource coming from? It doesnt seem to have one.

On the north view, the back of the head is darker than the rest of the body, I would recommend evening it out to match the body. A proper lightsource would resolve a few of the issues i can see with the base, so id suggest working on that.

Lineart wise, i would give him shoulders rather than having everything slope down from his head. i would also make the head a pixel or two higher above the eyes.

The side view's head looks to be alittle too wide. rather than expanding it because of the ear, i would suggest drawing the ear about two or 3 pixels away from the eye. The arms are definitely too long on the side view, and thicker than the legs. The head could also be abit more rounded at the top, rather than flat.

I cant tell how many colors you're using, so i wont get into that, but i will say, make sure you keep on top of that stuff, dont use too many. From the colors i DO see, i suggest giving your colors a bit more contrast, especially for the chest area. I would add a lighter color, and a darker color. That would balance things out quite a bit, especially when you get into shading him.


Animation.

This is what i usually do when animating a 4 frame walk cycle.

First you want to decide which arm is coming forward and which is going backwards. Accordingly, the legs on either side will be doing the opposite. That said, when your icon does take its step, it should always come down a pixel, to give it a nice bob in its step. For the arm going backward, you want to shrink it alittle, and raise it up. Afterwards, darken it. This will give it a sort of depth look, and make it appear to be further back, which is what you want. For this arm, the shoulder should come forward abit. For the arm moving forward, you want to raise the arm, apply no change to its color (you can, but its not necessary) and have it so the hand area is over part of the arm. Keep the size of the arm the same here. The shoulder should move back aswell. The same thing can be applied to the legs.

Your best bet is to use reference. Record yourself walking or watch someone else do it, and pixel your animation accordingly.

If you have anymore questions or if i wasnt clear on some things just ask. Hope this helped.