Good! But as always, here comes some criticism.
The robot is very flat, it could need some more shiny stuff to make it look more metallic. If you don't know how, try to use google to get some nice metallic surfaces so you can see how it reflects the environment.
You should try cell-shading instead of this smooth technique you're using now. Manga is very often using cell-shading and I think it's often the technique that fits the style best. It's meant to be cartoonish, so let it be cartoonish. Try to put in as many tones as possible for the best result!