Blather, rinse, repeat

Try adjusting the shading on his forehead and nose. The way you shade can leave the impression that his forehead is concafe and his nose is simply two holes for nostrils.

Otherwise the shading is fantastic. The shoulders look solid, and as if they have volume. The lapels are great. And I like the background. Whatever you're doing in those areas, keep doing it, because it's lovely. The hair itself is good, but work on the directions the hair is going. It tends to move in groups more or less circling the head, with a few lost, or dissenting strands.