I really like the concept of building your own tower defense paths. Normally in a tower defense game, you'd want to make as long and winding a path as possible, but if that path also provides city infrastructure, you have a dilemma! I think that has a lot of promise.
Bugs aside, I think my biggest issues were not knowing how much buildings cost and not knowing how to get money (there may not be one besides the steady income?). Without those, when I couldn't place a building, I wasn't sure if it was a bug or I couldn't afford the building.