I have tried a couple of other rock climbing gyms in Phoenix, and so far the Phoenix Rock Gym is my favorite. It is set up for the expressed purpose of climbing... and nothing else. This is a great way to get in a good aerobic exercise.
Another nice thing about the gym is that there is plenty of space. Kids and families usually stick to one area of the gym, while two other large areas often remain unoccupied. It doesn't get too busy and it's easy to find an open rope. There are a variety of routes available that can accommodate the basic climber to the more advanced.
I definitely recommend this gym and I plan on visiting again soon.