That's a great point that Jeremy made, but what grabbed me was the lighting. In particular the graduated toning of the wall and the girl's fair hair against it. All in all, a fantastic image for which I'm voting for too.
This is great, not only because of the fantastic composition, lighting and b&w, but also because of the story. The woman in the picture on the wall is looking into a mirror, completely oblivious of the woman watching her through the framed picture, and that woman in turn is completely unaware of the photographer surreptitiously watching her admire the art. It's a great juxtaposition of people and ideas.