I finished this the other day, but was not totally happy with the result. And I couldn't pinpoint the source of my unease.
A comment made was that the chin was too long and the forehead too high. So I did a tiny bit more shading and took a picture (see below) so you could see the difference.
One thing that is difficult in drawing faces, children's in particular: it's very easy to make them look much older than they are. Correct proportions are critical. And it's better to be able to add more later. Subtracting on a drawing (especially one that you've already sprayed with a fixative) is much more difficult.
See, now that I've lowered his forehead, and rounded his chin a bit, he's lost a year in age. I think I've added too much hair, but I haven't sprayed it again, so I may be able to lose a little without damaging the paper.
Practice, practice, practice.