Woah. The part you've got detailed already ROCKS! The buildings are excellent. You going to color it when done? I think it could benefit from a watercolor-type shading at some point.
I've fantasized about doing this style for my Haibianr city setting book...covering each district as a separate illustration. It would take me years, though, so it's only a dream.
Yeah. I want to see it develop. Keep going!