Very expressive back-lit portrait. Regardless of any rule of thirds, I like the extra space on his left. It enhances his thoughtful expression and "goes with the game", as it were. Good work.
Normally, I'd note that his face is in shadow. But, in this picture it works - almost as if you've substituted shadow for soft focus. This, combined with his expression creates a soft mood that his eyes and mouth hint is not the whole story. The depth of field assures your focus is where it should be, and there is nothing distracting in the background.