I could probably find and list fifty violations of compositional "rules" here ... I won't even try! I'm not fascinated by this as an example of "rule importance", but as an exceptional portrait/ work of art, in itself.
This is a *beautiful*, expressive work, It MUST capture a great deal of the personality of the model. Excellent portrait!, worthy of gallery exhibition.
What a lovely portrait. A great feeling about it... mysterious and brooding. I think someone else on apug has photographed this woman, she looks familiar. Anyway, well done!