Awesome job, the only thing I find is that it seams like either the Joker's head is too big compared to his hand, or his hand is too small, but either way it seams to me like the foreshortening is slightly off with the Joker, and it also seams like you did some real nice basic shading everywhere but forgot to shade Joker's face, one thing that I really like though is how the light shines threw the whole in Batman's cape, the glow effect you used there came out really nice, great job!