I have personally flow in/out of Sky Harbor many times, and I have also picked up/dropped off friends/family members several times throughout the years.
This is probably one of my least favorite airports to deal with, which I why at most I can only rate it 3 stars because it is just "okay" overall.
First of all, a few of the terminals have North and South curbs, which can be confusing if you are not familiar with this airport... sometimes they will shut down one of the curbs and you won't find out until you show up at the airport.
It can also be hard to navigate how to find your terminal because some of the signs are not so great ... I have literally run into instances where taxi drivers/uber/lyft drivers get lost, confused, and turned around in this airport.
The most challenging thing can be figuring out how to leave this airport to find whatever highway it is that you need to get to in order to get home... I usually always have the navigation on my phone or in my car going just to figure out how to leave the airport without getting lost and find my way home :)
The inside guts of the airport is very nice/good overall - nice bathrooms/restaurants/eateries/gift shops/etc... it is just one of the more confusing airports that I have encountered navigation-wise, so my best advice is to pay attention to the details when driving through this airport ... look for the signs ... and have your navigation on if necessary! :)