My main criticism of the sig is the contrast, I think it's a bit much on the background, and not enough on the render. I recognise the render from somewhere...TV or film...

Great effects, and interesting composition , but I think the contrast of it robs some of the detail.

My suggestions:
Up the contrast a little bit on the render
Subdue the contrast a little bit on the background (probably not much)
Sharpen the render, unless it becomes too grainy.