We have been on several Princess cruises (as well as NCL, Celebrity, Royal Carribbean, Carnival and others) and should reach Platinum level with Princess after this cruise.
But, over the years, we have noticed a degradation of service and I believe it unlikely we will ever reach the top Black level of Princess' customer loyalty program. Service levels have receded over the years and while in the past, Princess provided engaging onboard programs, the emphasis is now on selling photos and jewelry.
On ship culture seems to have become one of just going through the motions. No staff appeared to even want to provide a good experience to the passengers. In past cruises, staff often tried to interact with us, but on this cruise, they were very standoffish. Our first cruise, on the retired Royal Princess, was exemplary, but things have gone downhill ever since.