Ok, I have looked at this picture several times since you posted it. I also notice that you have used this model previously. First of all, as a model I've learned to like her because of her nearly demon-like features.
In this particular shot, I can't tell why she is nude. You even say: "the facial expression" is what really counts. If that's so, why didn't you emphasize it more??? In other words, the picture itself should direct the viewer and shouldn't need a caption that provides directions. I think there is a lot of potential using her in a more 'erotic' or villanous type settings because of her "look". I am normally not into that sort of photography, but I think she presents you with a unique opportunity. Not trying to be overly critical, but I've given this quite a bit of thought.