What do I see? Look! Down the alley. A shadow creeps. Barely visible; Then a fleeting, sharp outline in a dim patch of light. Others sleep, or are unaware. But I stand at my window and stare. What is that? lurking there?
I love the shot, but the noise is just too distracting. It's all the colors in the noise that ruins it. If only you could have gotten rid of all the colors in the side of the building, I love the yellows/oranges in the windows, just not the reds/blues & greens in the building itself. (long winded, sorry)
You should try using a low ISO, and in-camera noise-reduction to make the blacks look black and less noisey. You'll probably need to make it a longer exposure, but that might actually work quite well, especially if the people move while you're photographing them. It would be very creepy looking.