o.o I think it's actually quite well-done, the only detail I can tell you to improve is to ahm...make longer his hair, you know, more grew-up hair :) that's all.
All in all, you put effort making the appearance and the expression! Don't feel discouraged and keep it up! *thumb up* May the Valar be with you ^-^
P.S. Hentai strictively means "weird" or "pervert". There's a controversy between the definition of this genre as animated porn or a more deeper definition, but that's not the point of my comment so ^^ good-bye!