It is cold in the winter, but it's also hot in the spring/summer.

It is post industrial in the sense that the economy has moved on from industrial type stuff like steel manufacturing -- the economy is very tech/service oriented, with lots of computer/tech/robotics startups and so on, as well as a large health care sector (University of Pittsburgh Medical Center runs their own health insurance which covers a significant portion of the entire state of PA). It was one of the cities least hit by the housing crisis and the economic backlash from that.

As for dangerous -- there are some bad areas, like in every city, but for the most part it's very safe. Safer than any big city in CA for sure.

It is cold. It's not any more dangerous than anywhere else; it does have neighborhoods that aren't great, but they aren't like the worst parts of LA.

It's not horribly post-industrial anymore, although there is a significant contingent of mildly hickish people left over.