The top level is the best level in my opinion. It's the quietest level and you get a good view of downtown Phoenix from both the North and South side ceiling to floor windows. The only real drawback is the smell that comes from the DVD and CD section, I don't know it it's urine or just the plastic casings that are giving off that smell?
The cafe is closed indefinitely as I was informed by the librarian with no real date of when they are going to be opening it back up again. I have never had any problems with any of the homeless people that come to the library, but you might get asked for some change in the parking lot or asked to sign a petition by the entrances. The 2nd level is for studying and they have a 'quiet' room where you are expected to keep your mouth shut and study.
Why budget cuts!? The libs is only open until 5pm on Monday and a couple of other days. Overall, the library is huge and has everything you may be looking for. I want to get locked up like that dude Powder and read everything this library has to offer.