Sky Harbor is one poor gateway to the city of Phoenix and the Valley of the Sun.  It is outdated, super crowded, it feels dirty and it is the home of US Airways, the biggest carrier in and out of this airport.

Terminal 4 is configured rather poorly.  The terminal reminds me of a backwards E, like the second E in EMIN3M, except that there is another prong to the backwards E.  The concourses are not spacious at all, the seating limited, and consequently the crowds spill out into the walkway areas.
.  
To go from one end of Terminal 4 to the other necessitates using really narrow moving walkways which are on the spine of the E.  It is really hard to maneuver if you want to pass the throngs given the limited space.  The distances are long, the bruises will be many, either to you but most likely given by you as you negotiate your way between flights.

The other thing that must be mentioned is that Sky Harbor is not a business person's airport but rather a tourist airport.  I think that contributes a lot to the chaos.  When an airport is full of amateurs, like Sky Harbor, there are bottlenecks of humanity in all the wrong places.  Further exacerbating the tourist nature of this airport are the snowbirds who flock here so that they can seek skin cancer in all months of the year, not just summer in their native habitats of the Upper Midwest.

Get going on the remodel since it is long overdue and make sure you take in mind the tourists and the business traveler when updating this airport.