Fun time, but as others have said it's not really a big place--a few hours should suffice. Definitely dress casually because you could get pooped on or have some water drip from the ceiling. There are lots of hands-on opportunities, especially for children; be sure to bring a wad of $1 bills to drop in the donation bucket to take advantage of the feeding opportunities.
The penguin exhibit is the most intimate I've seen around, which is of course a great highlight in the Pittsburgh area. The outdoor condor exhibit was closed for winter and another outdoor display was vacant.
We paid the extra $5 for the Parrots of the Caribbean show. It was predictably corny and a few of the animals weren't interested in performing. I can't fault them (they are animals!), but I will say that show was probably best for little kids. Older attendees without kids might just want to skip the show and save the money for something else.
The cafe is more like a snack shop, despite the name brand sponsorship from Atria's. We had a loaded baked potato soup that was really good, but don't expect to get much of a meal here. Most of the offerings are things you'd see at a sporting event (chicken strips, pretzels, nacho chips, etc). They offer a few salads, but I can't vouch for the quality.
Bring your camera! Photography is encouraged in all areas except the show. Flashes are OK too. You can get some really great photos. I've posted a few of mine.