First of all, don't be so hard on yourself! Degrading your work in the comments automatically makes people think less of it.
I think this is very well done. I really like the shading and highlighting on the black part of his costume.
I think the highlighting on the face is a little harsh. It makes his face look "shiny" and it's also a little difficult to tell where the light is coming from. (I'm guessing it's backlighting, mixed with some dramatic lighting from directly above him, yet this doesn't quite make sense for where the light is landing on his cheeks.)
The proportions look good except his right eye appears to be larger and slightly higher than the left. I'd recommend flipping the image horizontally part way through your drawing to make sure nothing stands out as being misproportioned.
I think you achieved a serious and dramatic portrait.