Took the light rail to the airport and back when I was in Phoenix in April. It was clean, quiet, and air conditioned. The trains were packed during rush hour so I couldn't find a seat, but that just shows how popular it is. The stations are all very nicely landscaped and designed, with canopies and benches to sit. It was very easy to buy a ticket at the kiosk and also very cheap - I think it was $4 for a round trip. Definitely a nice alternative to driving. They also have bike share stations at some of the stations so you can bike to your final destination.