CMU grad here (EE, CE, Math '89). My wife is a native Pittsburgher. Her parents still live in the house she was born in – which I believe is not uncommon in this city. Anyway, I have her perspective too. Met wife shortly after graduating, got married, moved to Toronto to study neuroscience. After our daughter was born, we moved back to Pittsburgh to be with the grandparents. Can't say enough about how great an experience that was for our daughter. Pittsburgh is still very much a family town with deep roots and deep history. Daughter didn't go to CMU (had worked on robots there in HS and wanted a change) but if she had, she would have been 4th generation. Grandparents are great. Consider that you young adults coupling down. Are the soon-to-be grandparents in San Francisco?
Having lived and traveled plenty, I think I can give a pretty honest assessment of Pittsburgh. The first thing I need to share is that this is a racist city. Granted, things have improved from the 80s when most of my Pittsburgh-born friends would think nothing of using the n-word. But I dismayed how often I still hear it from thirty-somethings. It is something I've never experienced outside of Pittsburgh. Check out "The most racist places in America, according to Google" in the Washington Post. A city can be amazing in many ways, but it is going to take a serious hit in terms of attracting a global diverse tech community with that shortcoming.
But now for the good stuff. First, as PG discussed and others did mention, Pittsburgh is now a great food city. I think it easily holds its own against cities much larger. Seconds (and related to first) the city is getting more diverse. The fact that the universities have become so diverse (~80 non-Anglo-Saxon) plays a manor role in this transition. Most of these people will not stay in Pittsburgh, but their presence does change the culture. More and more are staying or moving here to start their careers.
On the tech front, things have been slowly improving. CMU and Pitt have always fostered tech spin-offs, but things are really changing now with Google, Apple, Facebook, and Uber setting up research centers. Without a doubt, this is going to change Pittsburgh. You can already see the changes with the construction of hundreds of $2000+/mo apartments in what used to be the "ghetto". I am hopeful that this will change one of the current shortcomings of the local tech scene – that this is an "eds and meds" town, and if you want to get funded, you are more likely to meet with success if your business in that space.
Pittsburgh has MANY cool, walkable neighborhoods. This is a huge draw for young adults. There are up-and-coming hip, walkable neighborhoods were you can still buy a nice house for $80K. FIOS is readily available. Taxes are pretty average. The weather is relatively mild (granted, I came from upstate NY). The geography is beautiful - the rivers, the hills, the parks, etc. We have an excellent system of bike trails. I'll be biking to DC later this spring.
Pittsburgh is very active on the city-data forums. There is no better place to put your finger on the pulse of a community in my opinion. You'll find many threads on the issues I've discussed here. I remember reading a couple threads worth paraphrasing. In one, someone commented that Pittsburgh must be a very rich city because it has more mansions than any other city. He clearly didn't understand the history of Pittsburgh and how much wealth was created during the industrialization of the early 20th century. But his assessment is accurate in that the city has WAY more than its fair share of mansions build during the timeframe when houses were built big and beautiful by craftsmen who cared. If you do move to Pittsburgh, do yourself and the city a favor and buy one of these diamonds in the rough and renovate. Another lasting legacy of the robber-baron era is that Pittsburgh has an amazing arts and cultural heritage.
In another interesting city-data thread, the discussion was on how Pittsburgh is still a place where people of average means can still live a middle-class life. The reason is two-fold. First, the cost of living is relatively low. But just as important is that Pittsburgh is a very hardworking and entrepreneurial city. This is the city that, in a sense, built itself and also much of the rest of the country. Steel, electricity, glass, etc. – they all came from Pittsburgh. That work ethic is still very much present. People here work hard, play hard, drink hard, and love their sports teams.
Sorry for the long post, but since so much of what I read on this thread wasn't about Pittsburgh, I felt I had to help shift the balance back. Finally, check out pittsburghtoday.org which will tell you most everything, data-wise, that you'd want to know.