Err.. scary.. I can only assume that youa re going for something stylized because this girl's head is not realistic.
I would say that the forehead is too large, The eyes too big and the bridge of the nose is too flat and almost in the same plane as the cheek bones. The lips have a good shape to them but the look like the curl out in a very unnatural way... I fi could see them from he side I would expect to seem them curl up and almost start to turn back on themselves. You should post a side view. Also the temples have too sharp of a pinch in them.
The skin shader is okay but a bit like plastic. The tones are good but the specualr is a bit too flat. Also the bump seems too large. The eyebrows look like they are black stripes and the hair could use less specular.
The upper lip is too bright and the eyes have too much eccentricity which makes it look like she has cataracts.
Hope that helps 
g
