I've been using Sky Harbor since 1979 and for most of those years was a very frequent user. My only, and significant, complaint is the roads and signage. They are so confusing and the signage is frequently so late in visibility to traffic that it is like a wreckfest trying to avoid people who are confused.
Requiring incoming passengers to walk across access roads in the terminals to get to busses and taxi's is asking for major trouble and is a major impediment to efficient vehicle movement.
Signs are sometimes located so they are blocked by overpasses until the last second.
Traffic is not monitored for speed so there is a big difference in speed between drivers not familiar with the airport layout and those that don't need to read the signs.