First off i would like to say, amazing work, you have great skill. So the first thing that sticks out to my eye is the hand, it looks to small for the size of the head. Also maybe it was not given as much attention as the face. The left side bottom robe area seems a bit under worked as well. I understand that the background fades in a bit there but to me it seems like it needs something. Looking as a digital image and seeing the real thing are completely different. I looked at the comments below and noticed that nobody has given you a real critique, or maybe you just don't post them. Anyway people can find things wrong in anybody's work if they would just say what they are really thinking about someones art. I think you have done a great job with this work and i will enjoy looking at your others.
YES proportion of the hand is 20% smaller. also not enough details in tonal variation are placed on it. I know hand is secondary to the face, but it need visual info. You can De-emphasize it by loosening the render OR blur it out a bit. but it needs highlight and darks.