Very interesting face. Why only half of it?
To me it doesn't quite work in portrait, maybe landscape, but I would still like to see a bit more face, or something in the background to balance. The highlights in the right corner, not sure about. Love the expression, all of his mouth would bring it out more.
great portrait.... i get it. you don't need the whole face to get glum, concerned, maybe indignant... giving half tells the story, and adds mystery, as well. Absolutely great!