I am a Pittsburgh native and haven't been to the zoo in years. Parking is free and you can bring in boxed lunches & water bottles, which was all great. Admission at $16 was definitely reasonable. Escalator was broken so we walked up the path, which may be a little difficult for older guests, strollers, etc - so wait for the elevator. As far as the zoo went, it was clean with TONS of new and classic old exhibits to enjoy. We spent about 4 hours walking through, some parts twice. We LOVED sitting on the porch of the Jambo Grill and watching the giraffes & zebras. Such a fantastic new addition.
Only negative I have is that I wish there were more water bottle filling stations throughout the park. Most of the fountains had such low pressure and were inconveniently located that it was hard to stay as hydrated as I wanted to on such a hot day.