Mind you, I know it might be be puzzling (considering) but I don't find the picture to be provocative.
I think it is a portrait that happens to show her back.
But then, I find I'm never in the mainstream on these sorts of issues...or, at least, where it's thought I should be
I think the portrait is equally an expression between photographer and model. I don't see it as provocative. I see it as classic.