The B&W doesn't seem to be appealing here. Add some color. Also, try to explore more techniques because all your sigs seem to look the same.
Two words : Tutorial Please. ^^ I'd definitely like to try to make this just with a different stock or render. CnC : I agree, add some colour. Not so fond of the border either. If it were me, I would also try to lengthen the effect on Superman's Chest.
Yeah, I said it a few sigs back, they all look the same. I think you should try something else. But other than that, it's not too bad.