Great Job I really like the effect you did. I'll give it a big 10 for the job well done but to make it a 12 I would give it a touch down both sides of the spine of the folder. Seeing that usable skin is not that big on a human I would have added Stiches to where it folds on the front and rear covers. The stiches would show it in three sections and a little erie effect.
I do love your shading effect great job