Looks good at four frames.

nice work

very neat!

 That looks like a pretty good walk animation to me : )

For only four frames, that's a pretty smooth animation.

The purple shadows make the sprites look... 'muddy'. I'd suggest using a bit less blue and more red for the darker shades. Something in between purple and red. That way you'll still have the blue hue change happening in the shadows without having the sprite become muddy looking.

Also, if you're going for a male baseframe, I'd suggest widening the waist a bit. Right now the waist is pretty slender, which coupled with the broader hips makes the sprite seem more female than male.

 i think if you could squeeze one more frame in it'd help immensely. Right now it looks like a march not a walk.

I like this.  Simple, yet very effective.

Good animation. Nice contrast in the palette. But the hips and legs look a little to wide, especially for an adult male as opposed to adult female.

 you palette is kida dark when it gets to purple