For the back view, I find myself agreeing with what Random said, that it seems weird for the hat to go from side to side instead of bouncing up and down like the side view does. If you could pull off a bounce for going upward, I think it would look loads better.
Btw, I really like your work darklink45 (I might have already said that..?). Your style is unique, and that's one of the things that I like most about these sprites.