At least for me this is a hard shot to comment. I can see something poor on the woman's face, but wouldn't know what it is. Since you said, i agree it's the light. I probabbly didn't know what was it because i don't know anything about this subject (light and stuff). I read a few days ago some things about reflectors, just a white board or paper to reflect the natural light on her face, i'm sure you know that kind of thing because you have 94 years and 3 in dpc (:D) but maybe that would help. The worst part seems to be the left one, the light there doesn't help her skin, hair and makeup.
Talking about the composition, i think the little piece of background at the right is distracting. I would prefer to see background everywhere than just that little piece. But the best choice would be a different perspective showing only her face and the hat in my opinion. This perspective is giving more emphasis to the face than the hat.
The makeup is nice and i like her boring expression. And i think it meets the challenge well.
I hope i could be helpfull and you don't get offender by my giant newbie comment.
Cheers!
It is not easy to make portraits of people in hats. I don't know whether you used anything to lighten her face - something reflecting light to get rid of shadows under her eyes. Good idea, nevertheless :)
*not voting as I'm in this challenge-just commenting since I've seen requests for comments in the challenge thread*
Love the attitude in the expression, and the hat is super cool. Would help if you had a larger DOF so that the subject was in sharp focus throughout. Also if you had gotten some light up under her hat to light up her eyes a bit more. You can tell she has stunning eyes. some strategic light placement would make them incredible.
HTH