some anti-aliasing could smooth this out, though. Also, some parts such as the hands could stick out more, right now the bottom part of his body looks like a big, pointy mess, if I may be so rude. Also, the guns sticking out of his chest could look a bit more like they're actually going out of his chest; try adding a thin outline to make a slight bulge effect where the guns connect to the chest.
Other than that, I love the colors and your lineart is superb.
7/10, good, could be better.