You're off to a good start. I look forward to seeing what the finished map looks like.
The only (minor) criticism I have at this point are the buildings that comprise the city. Is there anything you can do in photoshop to make them a little bit more shiny or sharp? They seem a bit drab as is.
I guess I've been influenced by the city maps Mongoose did for the Conan rpg. You can find a city map they put up for free at http://tinyurl.com/2t496s to get an idea of a map thats distinctive but doesn't look like an explosion in a Crayola factory.