I loved Delta at LAX and at PDX but it's just not a very strong presence in PHX. My review here isn't about Delta on their flight quality or service but related to the Delta terminal 3 at PHX. I think it's fine flying into PHX on Delta but probably better to fly out on a different airline.
They did not honor my TSA pre status even after reminding them the pre listed on the boarding pass. Ended up having a terrible experience going through security - and lost a lot of time.
They also don't have any lounges so don't expect to get any work done or peace and quiet if you have a layover or are early to the airport.
Also there are hardly any shuttles between terminal 3 (delta) and the rental car return center. I saw five terminal 4 cars come and go by the car return place before finally a shuttle came to pick us up to the terminal.
Also signs inside the terminal are not very well displayed -I.e. general gate signs, monitors, etc.
I definitely did not feel like I could plan out my trip in and out of PHX Delta within what I had initially expected as reasonable. Do yourself a favor and fly US Airways, Southwest, or another airline out of a different terminal.