Dear Chuck,
I posted in another forum about losing edges earlier today. Be sure to let the flesh at the hairline break that hard line of the hair. Also, the left side of the shirt by the arm has a dark line all the way down. The original photo has matching values near the armpit. I think that sometimes because we "know" that "this is the line of the shirt" that we draw it and paint it that way without realizing that the light would never stop dead like that.
I tell my students that the darks that we make are like rivers and that the light on either side of the dark shadows are the "land". Now, how does one get across a river? Either a bridge or stepping stones is the answer. Your photo proves that there are bridges of light (diagonal patterns of light) from the arm to the chest and I know by observing other pictures that I have seen of yours that you would put this in on your finished piece. But I think that it is important to always block these things in perhaps even when doing the underpainting. I think that you have a great start here.
Your paintings are really wonderful and I greatly admire your talent.
The only other thing that I would say is that the eye on the right seems to have a larger orbit than you have painted. Using the clock face as an example, in the photo the eyefold line is going from 3 or 4 o'clock on it's right to about 10 or 11:00 on it's left and you have painted it from 3 or 4 to 9 or thereabouts. Change that line and I think that you will be very happy with the likeness factor. But as I said before, I am very enamoured with your work and I know when this gets finished that it will look like him. You are brave and very very good.
I hope to have some pictures up soon for you to critque for me also.