The first thing that struck me when I saw this was how bland it looks, despite being so well made and detailed... So I threw it in Photoshop and upped the contrast a bunch and saved it with 20 less colors than the original. It needs saturation! Normally I don't mind pale pieces, but this is Mortal Kombat we're talking about! This is how the Photoshopped version came out.
Don't you think that looks better? You could easily drop 15+ colors from that, too, with some manual color replacing. 60+ colors is seriously... far too much, for anything involving pixel art. Especially a piece with so few basic colors, like this (it's got skin, black and yellow, a small sprite of the same character could easily do with 10 colors for the whole piece).
Anyway, colors and contrast aside, I think it looks great. The face looks very unfinished compared to the rest of the piece, and the outlines could do with some softening and/or AA. Great job.