As of now the render just seems "there" if you know what i mean. Maybe add a c4d in front of him for blending, and that will help your depth a bit too.
doesn't seem to be a whole lot of 'blending' going on between the background and the render. try to make it look less like the render was just sort of slapped onto a background.
Like others have said, blend the render into the background a little more with gradient maps, photo filters, etc.
