I have no complaints about PIT - I travel as few times a year and have never run into any issues. They have great shops, better than most airports, and it's a shame that the shops are no longer able to be open to the public because there are some unique stores there.
Overall the employees are friendly enough, particularly at the airline counters, and more specifically at Southwest Airlines. I have recently developed some mobility issues and they've always been great at helping me with getting pre-board and making any accommodations necessary for my travel.
The airport is always clean and it's easy to get through the terminal because it's not too big. Definitely love that we have such a great airport in Pittsburgh.