remade the whole piece, I guess it's better now 

His gun looks a bit big and thew shading towards the bottom needs to be smoother and better.

I wonder why these things get accepted, even with those clearly evident problems ...  

try not pillow shading

I think it's the last boss in mega man zero? Anyway Metaru is right, you need to work on the shading. Imagine a light source from one point and shade accordingly.

You could also up the contrast on the jewelry so it shades to pure white or close, looks more shiny.

that exelent lineart gets ruined by the poorly pillowshading you've made.

how about a bit more info on what is this?