I don't know what it is, maybe the difference in saturation/exposure between the focal and background or maybe it's just me, but it feels like a space stock background and a stock of a woman blended in with a soft-brush eraser tool around the edges.
Looking closely, I can clearly see the amount of work and technique you put into the various elements, but I just can't shake my dislike of the complete, overall product. Nonetheless, my tastes aside, it's really good. Nicely done. It makes me want to get back into photoshop