The hair fade at the edge near the left ( her actual left ) which immediately told me it was composite.
Don't know what you used to cut the render off but I generally use the technique of making a bold selection around the subject I want to cut and then use the "refine edge" tool with smart radius. It help a lot for those hairs. Doing this manually and having good result is nearly impossible if you don't put many, many hours into brushing your subject out. It is also not required since the introduction of the refine edge tool in Photoshop CS5.
Just my 2¢, I like the concept however, and the fact that the lighting don't fit actually give the image a little somethin somethin'