I have spent the last 20 minutes staring at this wondering what was bugging me about it. It is the eyes Well, not really the eyes themselves, it is more the markings around the eyes. They are wrong for the angle of the head. The eyes themselves are different sizes, but thats an easy fix with black, not so sure if I can fix the other problem so it doesn't bug me enough that I still finish this.
I have made slight changes since this photo and will have a look at it tomorrow with eyes that haven't been staring at it all afternoon.