I have the slight feeling that the original image using in low opacity.
The lines of the face, the shadows do not match. In a straight and firm look. And the shadows look very real. Likewise, the use of brushes discard your work as a vector. They look unfocused. Out of curiosity how many layers you used? At least I reckon 200-300. I think you need to improve in the use of the vector. This looks more like a photomanipulation. Now the design is poor in idea, render this big needs best match. I see the low quality of a background to the height of the render.