I am a complete fan of the Pittsburgh Symphony Orchestra and I attend many of their concerts. I was lucky to take a tour of their building, and on one of the walls backstage I saw a picture of Richard Strauss with the PSO from when he appeared with them as a guest conductor. That's just one example of the rich history and tradition of the Orchestra. But the Symphony continues to make history and remains one of the top 10 orchestras in the United States.
If you are attending a concert, the sound is excellent particularly up in the balcony. If you are sitting underneath the balcony, I don't feel you are getting the complete richness of sound that you get elsewhere in the hall. So you best bet is about row N and forward downstairs or anywhere up top.