You must not have been to all parts of it. There are some very grungy, crowded, run-down areas as well.
(The nice parts are pretty nice though.)
Like almost every city on the planet.
Of course. But for the most part it's beautiful. My best friend used to drive taxi and when I had nothing to do I would go with him in the car while he was working, so I've been around. I like the architecture in the barrios.