I had to look up who this was because I didn't recognize the name of this person. Now I hope what I have to say makes no offense to you. But I would like to give you an honest opinion. So I'll start with the good opinion(s) first. I love the shading you used. I personally can never get it down as good as you have it Also I love the way you have done his hair, it actually looks like hair! You have put great detail into his face and clothes in general. I especially love the details you put around his eyes and as I said his hair including his facial hair as well. Oh and I like the way you did his tie too! Ok, now the only thing I see that could use a little bit of work is the alignment of his face. I could be wrong, it could just be how you have the light shining on his face. But I looks like his mouth and nose are at a bit of an angle compared to his eyes. Other than that, everything looks great! Again, if I am wrong, and it's just how you have the light shining down on his face, then I apologize for not seeing it correctly. All and all, great work!
You seem to be very hardworking But there is a common problem in many of your drawings - eyes, nose and lips are displaced and do not lie on one axis. Also the eyes tend to look in different directions. Draw construction lines and look on the drawings through the mirror - this helps