I'll keep it short and sweet.
- Overfilling parking lot. Good luck finding a stop to park your car. You may have to park on one of the alleys and hope that you won't find your car scratched/dented when you get back.
- as you wait for a good 20 minutes or longer for a shuttle to get picked up from the terminal you'll watch 2-3 shuttles from other PHX parking lots pass.
- pretty rude staff at the booth. Slow checkout.
Bottom line: spend a few cents more and park somewhere else.