The hair doesn't look consistent... like how in the front you have lots of nice sharp points... and it gets softer toward the back... as if you got kind of lazy...
And... the hair (facial hair included) needs a wee bit more shading... I can see where the light source is by looking at the skin... but I wouldn't be able to tell if I just looked at the hair.
Put some more work into it... try to make the hair look a bit more uniform... and maybe play around with saturation in the shadowed areas...
Well, I know there are still problems, but working on the same pic too mcuh time is boring, you know... oh, and I hate drawing hair, really. I'll probably learn it, though... soon...
