I lived in western PA for 15 years, and for about 10 of that I was forced to fly US out of PIT fairly frequently. I've had my worst airline experiences on US. Usually about 1 flight out of 3 included some awful incident--lost luggage, horrific rudeness, incompetence, you name it. I always used to say, "Working for USAir means never having to say you're sorry." Because they didn't, no matter how bad they were. They never apologized for anything. The other thing is that they tended to COMPOUND problems. They would screw up, and then screw up again trying to fix it--almost as if they were trying to discourage you from ever bringing problems to their attention. As if that weren't enough, they way they screwed Pittsburgh was unconscionable. There are other topics in this thread about that, and others disagree, but I was living there. US was incredibly shady and double-dealing on multiple occasions.
On the other hand, screwing Pittsburgh meant the other airlines moved in to take up the slack, fares went down, and I could avoid them. Now I live elsewhere and hope never to have to take them again.