Well, to start with, there is something that sticks out a bunch that I feel should be fixed first. Now remember, I'm no anatomy expert, but the legs are far too short, and I would guess that they should be about a "head's worth" longer.
Next, I think that the highlights on the clothes should be addressed. It is unnoticeable at 1x1, which poses a problem--try adding some contrast between the base color and the highlight color.
But on the flip side, I compliment you on the way the metal's shaded, and on how you've achieved a very similar armor structure to the original. With some touch up here and there, this piece will be keen in no time. Good work.