Oh wow, I went and wrote up a little critique and even did a quick and dirty edit focusing on the linework, thinking that you did them yourself, but I guess you're just looking for advice on the coloring/shading here. >_<
Well, I'll still try and help ya if i can.
The blue you have on the cape now has noble intentions, but looking at the space it occupies, it just doesn't coordinate with the subtle ambient lighting you have on the arm and hair. In my edit, I reduced it to a simple outline on the edge of the cloth, which I felt more consistant and pleasing.
Also, when you were coloring this, it seems like you were thinking within the borders of the outlines themselves sometimes, and not realizing the full depth of the form you could explore. Some areas you succeeded in, like the right armpit in shadow. Other areas like the part of the cape farthest to the right are what bring it down and make it flat, when you've got the darkest red bordering the whole shape.
I remember not too long ago, I'd get all awesome on things like the deformed arm, where there were small tight lines and constrained spaces to work in that are comfortable, then I'd move on to a more open space within the same piece(like the cape) and not know what to do with myself. That may be what's going on here, but eventually I learned the importance of blocking in the darks and lights and making myself a good roadmap so i could envision where the figure sits in space before I started pushing pixels. So mess around with that, don't be afraid to bust out the cast shadows, even if they obscure the figure, and don't cross until the little man shows green.