I think that the face looks a little flat- the nose's probably the culprit :) Her head's pretty much fine but the neck and body anatomy could use some work. She's a bit vacant looking, not a very interesting portrait.
Here's an edit, she may look more mischeivous than what you were going for.
something about the anatomy, just doesn't look real, can't quite say though. The hair is a real work of art.
Why use a dark outline for the hair but not the neck and shoulders? Great work overall, better than anything I could produce in pixels.
great use of color, i looks very lifelike