The first post commented on the proportions of his arms; OK, this nitpicker will say that it looks a bit to me as if his right hand is slightly forward, which will make the fist look larger and the arm look shorter. (A great trick for an artist to get it all in the frame!)
His expression doesn't look worried to me. He just seems to be lowering his brows to shade himself a bit from the bright light. His gaze seems to be confidently steady.
Where can I get his shirt material for my own use??