I like it, but the back guy's top head isn't blurred. Also, if you could add a bit more c4d effect to the front-bottom-right, it would give it some more depth. Sort of coming off of the gun/shoulder.
Seems a bit oversharpened in some areas, could use a bit more depth, and lighting work. I'd say colored version is better, but it is a bit monotone. Thats a hard Render/Stock to work with (I tried both ), neither came out to well for me, so I commend you on that ^_^.