For the subject, this is a bit too dark for me, and it seems a bit out of focus. I think more sharpness would bring out more of the detail and definately bump up the score. I do like the intense blue tone though.
I like how you composed the shot. The flow of the dress especially as it runs off the edges. All in all the subject feels well balanced. The thing that I don't like is the lighting. I like dark images but the lighting here which I assume is ambient just doesn't do anything for me. It lights the subject but nothing more. The part that works the best is on the dress which enhances that flowing aspect. The rest however just looked muddled. Also, the focus seems a bit off. When I look at this my eyes go to the bottom of her dress, which isn't entirely in focus. Maybe the faces are but it's hard to tell due to the lighting.