Well i really like the atmosphere you have some lightning flaws. For instance, the things on his back that stick out make it seem like the bright light source is behind him. Same goes for the top of his head. If you look at the very bottom of the things that stick out, they also are enlightened, which doesn't feel aligned with the lightning source above the head where you placed it. Not to mention some parts on this back are also showing an enlightened touch that isn't aligned with the lightsource. Also the green lights on the back that are under his arms doesn't give away any reflection on the parts it would hit him, although the green light on the left does that to his right(left for us) arm. So thats the lightning.
There's good amount of depth in the tag but kinda lacks too much stuff infront of the render, well, lacks C4D in general to make it have a decent blending with the render. Though the atmosphere is so good it kinda makes me forget about it >_>. It lacks a text too >_>.
