Proportions are off on this one, you might want to make his legs somewhat longer, shrink his head by a pixel or two and shorten his right hand a bit in frames 2-4.
Also while you kinda pulled of the way metal looks, the light source doesn't seem consistent.
Shading in general is a bit inconsistent.
Now, this one could be ok, if it wasn't fot the giant head.
Colors you use are kinda dull(for the lack of a better word), but proportions and shading (to some degree) are much better than in the other picture.