I'm loving that hairdo.
You might be simplifying the face a bit on your statue. The nose is very angled and the other nostrill should be showing. the eyes are exaggerated, which is a very common thing to do, and a lot of the shadows have been left out. I would suggest you try to redo the shape of the head a little and maybe scale it down a notch as it makes it easier to correct and spot faults. I tried to change your head based on the reference:
The right side of the head (our right) has a lot more curves to it as ticks closer to the eye. The eyes, nose, mouth and left side of the head has some pretty deep shadows that help bring out the volume. He also has a minor lightsource comming from the left.