Cool! I like! Now on with the critique:
1) The linework on this one is IMO your best. Keep at it!
2) I love the face, nose and eyes. Just wanted to say that.
3) The ends of his hair are a bit unusual. Looks more like fabric than hair.
4) I like spot detailing on his hair and collar, but I want more. Along the bottom edges of the coat and sleeve/pant cuffs, maybe? It seems to be concentrated around the head, whereas the rest of the body has general coloring and thus comes off as unfinished.
5) The line of the sleeve cuff bugs me. Me, I'd erase it and let the color shadow imply the thickness of the coat fabric.
6) I generally like the pose, but I'm uncertain what his right hand is doing, and his left leg is off somehow. Try standing as you imagined it in front of a mirror (or your sister) and then see if the pose can be held.
Here endeth the critique by me. Do with it as you will