Nicely eerie. I enjoy his grin and his eyes and the spiky bits over his eyes and under his shoulders and the way the barbs on his hands face eachother and almost seem to form a second mouth. And the dark red background makes a good contrast for the green skin. Shading seems a little patchy in texture - maybe try a different brush tool on the darker green sections? Of if you wanted a soft color transition, could try using a shade a green between the darkness of the deep shadow, and the main part of the skin... Don't know what program you are using or what tools you have available, though.