The PHX zoo is a great place to take your kids to look at large, charismatic megafauna. However, if you are like me, you go to the zoo to try and learn something about the natural history and ecology of the animals on display. There is very little of this, the farthest that the signage goes is to tell you the continent and maybe, if you are lucky, the country where the animal lives. The zoo is also mammal heavy. Don't get me wrong, I love a good mammal display, but I also like to see a nice collection of amphibians and reptiles. If that is what you like to see, the PHX zoo is not the place for you. They do have a small collection of southwestern rattlesnake and some common pet amphibians, but that is it for the herps... They also have a komodo dragon that is pretty large but overall, they lack the fish, amphibians, and reptiles. Also, where is the insect collections? Maybe I missed it.
The animals do have very large enclosures, but some look under kept. Also, there is one aviary that is very cool and has some very pretty bird species. They have red eared sliders hanging out in the ponds on the grounds that are probably the reason sliders are in natural waterways now... a shame...
Overall, I was pretty disappointed in the PHX zoo, the admission was pricey, and the breadth of animals small.