Well, the idea is pretty good. Well made in some parts. (top and under of eyes and some face parts)
I need you should remake the top, the mapping will look really strange in the sphere. You need to make curve lines, not straight ones. Look:
Maybe change the eyes, make something realistic. It'll be much more frightening.
Maybe you should make the lower jaw.
About the colors, I don't know if you made to use by yourself. But I think a red colour will fit way better. Red will remember flesh/muscles.
Continue with the good work.