I just spent a month in Mexico City and it is such an amazing place (food, people, nightlife, history etc.). The fact that such a large city is built on a lake in a valley is astonishing.

I agree that flooding was a problem. The roads routinely flooded (although remained navigable) almost every night because it was rainy season. I was fortunate enough to stay with a privileged family, so shortage of water is a new concept to me, although totally believable. The traffic and congestion in the city was crushing. I think it would be a more enjoyable and drier place if they had not constructed all the roads and parking lots.

Either way, I highly recommend exploring this city and its amazing culture.