The way you colored the background is beautiful as it gives off a lot of detail. Except the metal fence on the right bottom corner, it looks far too dull compared to the rest of the environment. I would have added more rust, stains or texture so that it fits in with the highly detailed surroundings. As for Agent 47, you could have added more detail to his hands, especially to his left hand so that it looks more like it's tightening the silencer with a little more effort.
Illustrations that contain small tales within them when unraveled is something I like to take my time to admire, and in this case there isn't much to contemplate. I'd like a little more conflict, for example:
Agent 47 body leans against a brick wall while glancing around the corner, only to find a couple of guards inspecting one of his recent victims, strangled. He prepares himself to his next encounter by attaching his silencer to his silver encrusted pistol, while giving off a focused yet soothing look on his face.
Overall, this is a superb piece of work, don't forget to keep on improving! :D