I certainly see nothing wrong with the background. In general there are two type of background images for a picture, one is a backdrop and the other is for environmental/mood setting. This one does a fine job for setting the mood of the picture, by that, I feel that its creator is a good job. And you can tell him for me. As for you work, the girl is great, the costume is wild but nice looking. It all comes together just right to create a unique looks that is beautiful. With the wrong sort of background, such a composition would have the same impact. And you can pass that on too.
Pangor