good choice of butterfly style lighting, however, it still seems a bit harsh. diffusion from a softbox or any sort of transparent layer might have been better.
the light from above has created unflattering shadows under her nose and chin- try lighting that's from a lower angle next time. also, a flatter background might have helped, or simply using a wide aperture (eg 3.5, 2.8) for a narrower DOF.
needs more light, expression on face is a little along the lines of "i'm not sure i want to be doing this...". blue background is pulling eye away from subject, perhaps too "busy" with the texture (and brown top is too much contrast in colour). should probably not use straight-on flash (can tell by reflection in her pupil). try moving the light a bit to the photographers' right to fill in her face more with details.
I'm not sure that the expression on the face of the model makes a positive expression with the viewer. she almost looks scared. the background is out of focus in a bad way and looks a little lumpy. the clothing choice for the model is sending a negitive message to the viewr and her hair on the left side and her chin are making for a shadow.
The lighting doesn't seem right and I think that she seems a little uneasy about doing this. I think that has a negative effect on the picture's appeal.
Beautiful pose and smile. The background really clashes with the browns. Would like to see more lighting on the gal's face. The shadow under her nose does not flatter her.