What is Awesome~!
You did an excellent job on catching character, you can really see he is a bit of a scholar. Maybe even a magic user. Your cell shading is very well done, it really shows the folds and texture in the clothing. the bright blue book is a nice touch, it takes away from the darker colors a brightens up the mood. The background is a nice touch.
Anatomy is one, the head seems big for its body and the arm seems slightly out of place. Maybe take a step further and work on your facial detail. The eyes are very well done, maybe add eyelashes in his case they would be facing down to look like a man, you don't want them flicked up.