3/5. Good concept for a game, but it's too easy to lose, even on the lowest difficulty. The opponent can cut off the only lines connecting to the goal, and you automatically lose. You could also change the difficulty bar from a bar to just buttons (an Easy button, a Medium button, etc.). If those was fixed I will give a higher rating.
There should be different servers for the level of your city, like a new level 1 city is with all the others, so when they're noob protection is lifted, they don't get raped by the level 2 and 3 cities, and same with 2 vs. 3, 3 vs. 4, etc., ect.
It would clear up lag since there's only one server too.