Interesting the first few times
I liked the simplicity and the smoothness of the graphics, along with the intuitive interface, but found myself wishing for something more. Perhaps the ability to plop down parts of the city in different areas (which could affect what the player could build later on) would help to make the game more enjoyable over multiple runs.
Also, I would have liked to have seen some way to restart the game mid-way through, when it became apparent that my latest stab at making a cityscape was going to be about as successful as my last (read: 30 points or so).
Keep up the good work!