I'm a terrible critique, but it would seem as though your matte, flat painting style detracted from a lot of the chrom-y reflection that was in the pencil sketch. That said, I have a great respect for artists who have a unified enough view of the world to re-iterate classic characters like you've done here with Ironman.
marvel is very lucky to have your talents on their side! i just hope they dont start making you paint like disney comic covers. "ultimate iron monger VS. daffy duck" actually i would probably buy that to be honest.