I've been staring at this thing until my eyes bleed, and I need some fresh input on it. What can I do to improve this lighting?

The basic background is the wonderful Whitechapel Construction Set from RDNA (with Ian Porter's free hansom cab) and I'm trying for a foggy, spooky Jack the Ripper type ambiance. I've calculated the lighting very carefully to parallel real-world luminosity from this kind of flaring gas lamp, but at this point, I can't tell if I'm getting close to that or if this is just a dark opaque mess. (Part of the problem is that I'm worrying about the gamma correction; my monitor is gamma-corrected, but when I've seen this image on other monitors, it looks so dark that the details and colors are mostly gone. So I'm wondering if the problem is the other monitors, or the original image.)

Anyway, before I add any more figures or procede further with this, I was really hoping to get some input. I've looked at so many renders of this scene that I can't judge any more. Comments, suggestions, etc all gratefully welcomed.