According to my profile statistics, this will be my third critique using this widget, so I'm still pretty new to it, but I'll give it a shot. Please bare with any possible spelling mistakes and/or vague naming of objects, English IS my first language, but chances are I'll miss something when I proof read this.
So where to start? Firstly, wow! I was immediately drawn to this as a thumbnail in my inbox and I just love looking at all the details you've put into it. That intricate gold baroque-like metal work you've got happening in the background (I think it MIGHT be a chair?) is just gorgeous. I think the way its contrasted with the simpler design of your character and his clothing, really draws the viewers eye to him, which is great. I also really like the pose he's in. In a way it's a very simple pose, but it shows a powerful character and appears quite natural as well.
Alright, since this IS a critique, I better get to that bit, since I'm sure I could find plenty more to compliment about this piece.
Light and Shadows:
Your characters face doesn't seem to be lighted properly. For the way the majority of objects present seem to catching light in the image (from the front), there is too much shadow on the lower half of his face and his nose appears to catch light from the right, leaving a singular shadow on the left (his left that is). Often if you were to see a side profile of someone, you'll notice that their chin protrudes outwards a bit, this would catch a little light as well. I also thought that the way you've chosen to shade the collar bone makes it look unnatural. The "Y" shape you've shaded under the collarbone is quite thick, and wonky, in a straight position like this, it would be slightly less defined and straight.
When working with this much detail, I imagine sometimes you feel like just leaving certain things. But there were a few areas I thought could use a bit more definition. Mainly the tassels and the pom-poms on the headpiece. The tassels I think need a few more lines like the fur on the headpiece and the pom-poms a fluffier feel.
I'm admittedly still quite new to this area, but I thought maybe the collarbone was slightly too high (really little bit though). I noticed the chin is slightly longer on one side too. This is common for people to have, but I felt the sort of regal air this image has to it called for a bit more symmetry to match the surroundings. The other anatomy thing I noticed was the hands. I know just how annoying hands are and you've done pretty well in my opinion, I just thought the left hand was quite a fair bit longer than the right.
The only other things I could find that could possibly be improved are the swords ribbons (I assume its a sword). If light were to hit the ribbon front on, it would hit both strands, rather than the one. And I think the shoulder pads would have more shadows on them from the headpiece too.
Overall, I truly think this piece is incredible. And I envy the amount of detail and emotion you've accomplished putting into it. It's a great piece.