I started playing around with the environment. Made some tweaks here and there to the face and played with the lights. My idea for the scene is him standing on top of a mountain, on a ledge, with the sky behind him and the skyline barely noticeable at about where his knees are.

I created the shader for the rock using a displacement map (and bump map) of a rock texture I created in PS. the same texture was colored and used for the color. I also added an occlusion node to the color that I need to tweak some more to fake FG where the shoes meet the floor.