I also really liked the ending. The mysteries are a big thing to bear, and is quite bothering, though. The structures have that futuristic and mechanical feel to it, and that showed clearly at the ending. It hints that aliens built it. But, I thought Shuichi or Kiries ancestors, shamans, casted a curse over the city, and that it would have some kind of magical ending where Shuichi would have to perform a sacrifice to save her and the city.
It's bothering me, that this will happen indefinitely and forever. I guess not, Uzumaki! I'm dying to see the curse trying to bugger the humans from thousands of years in the future, with their cosmic weapons and ultra intelligence. So it's a fake Uzumaki, ha! Take this name, sucker, you deserve it. This city went through hell.
The position Shuichi and kirie ended at is very "romantic".