Great expression.

The mustache looks off, but I'll assume that's intentional. Broken nose? :P
Why not use colors from the face to add highlights to the hair?
and the cheeks stand out too, largly as a result of shading around the mustache. should shade as if there was not a mustache on the face, as the mustache would not make the cheeks protrude, but rather cast a shadow around the area.
That said, compliments from grave apply with me as well. ^_^

I love the colors on this. Like an old photo, but still not THAT old.
I do however not like the blocky shading on the neck.

also, the forehead seems to be pillow shaded.