As a ski-only resort I had my reservations about what the resort would be like, however, I had a lovely time. It's immaculate, pistes are well maintained and all aspects are 5*. With limited numbers of lift passes that can be purchased each day, you feel like you've got the mountain to yourself.
If your based in Park City, then it's definitely worth spending one day in Deer Valley (an Uber is only about £20!).