We come here mainly to take my daughter to the weekly playgroup that Phoenix Children's Hospital (I believe) sponsors. She loves it!! There's a really good selection of kids books. I'm not much of a reader (gasp!) so I can't say much about the adult selection but hubby (who is a reader) seems to like it. I think they have a thing online where you can request a book to be available at a specific library so you can always go that route.
The best thing about this library is its location. Granted, out of the way and nothing near by but homes and a BEAUTIFUL view of the White Tanks. If I didn't have a kid, I would just sit in there all afternoon with a book or magazine and check out the gorgeous landscape. The architecture is also very nice. Simple, crisp and blends well with the landscape.
The library is connected to the park so before or after your time at the library, you can always do a hike! If you are in the area, definitely check it out!