A very dramatic and nice portrait.
I agree with Maris Rusis regarding the metal accents at the collar but I add something else:
Could you clone the rod (?) at the far left ? It looks like there is a window there... yes it is !
And at the bottom left I would also clone that spot of grey. No, not the one from the sofa ! The other one lower...
The darkness of the portrait doesn't bother me at all. Perhaps a little bit more of contrast (or clarity) just on the lighted side of the face... something to try perhaps...
I also like the very shallow DOF. Is this portrait one among many or is it a "lonely" one ?
I dared to work on you image. Should you consider inappropriate I will remove it. Thank you !