Extensive review:
* Shading
Not a whole lot of shading here, Kazzo. try to apply some more highlight at least on his shoulders. I realize the wrap is hard to work with and that adding highlight somewhere will make highlight somewhere it shouldn't be any, but try anyway - it will end up looking more dynamic if you do.
* Colour
It's pretty monotone. Try to use some of the colours that the particles produce, some more acid green on the skin itself would make it blend better, and the fingers and toes (that cannot be changed) would look better.
Considering he's put together by various parts of metal, try to use slightly different shades of metal-colour for each part.
* Concept
It's a metal infernal, not much of a change, really. You could try to make something out of the face to give it character.
* Detail
Mediocre, try to do the aforementioned changes - more acid green in particular, and some design to his face.
* Wrap
It's not really your fault that the fingers and toes stand out as much as they do, but try to make something good out of it. Make the fingers blend in and look like they're coming out of the hand rather than being attached to it, the same applies to his toes.