I can't think of a major airport I would give more than 4 stars to, so this one ranks pretty high for me.
Sky Harbor is HUGE! Do not book a connection for under one hour unless you thrive on stress and love spending time in airports.
This review is for Terminal 4 the USAirways terminal There is a nice variety of food and shopping options past security. The gate areas are bright and open and the available seating is adequate. The corridors are usually easy to navigate although it can get quite crowded at times. Everything is well marked. Generally the staff, both airport and airline, are friendly and helpful.
There is free wifi. A big plus for me. A few more convenient outlets/charging stations would be nice.
All in all this is not a bad airport to have to spend time in between flights.