What a warm, sweet smile!...I can't imagine that you could get such a genuinely nice reaction without a terrific working relationship...well done! One small nit, though, which is that the little bit of her collar is the same tone as the surround. If it's different in the print, great, but even so I think I'd burn that area to get it lower than the value of her face.
I like the composition of this shot, the way the head has been placed in a dynamic way on the diagonal of the frame. The girls expresion is very pleasent, however I do think the picture could be improved by a small light behind the head with a snoot on to seperate the head from the background and stop the models head from disapearing into it