To go back to the original question "improving or on a downhill run?", my feeling is that Princess in on a very rapid downhill run. When I first started sailing Princess, it was like the Nordstrom of cruises. Then it moved downward to Macy's. In June, I debarked from an 18-day Transatlantic on the Island Princess, and let me tell you, it was a Dollar Tree cruise. It was truly the cruise from hell. Food was awful, internet non-existent (even in port), surly crew (new experience), never received a fully correct order from room service, etc., etc. Little problem with medallion, rather liked it once I got one with a live battery. The system is just not as sophisticated as advertised.
This last cruise did it for me and Princess. (I didn't write about the worse things that happened or didn't happen.) Just booked a HAL but have some concerns because Carnival combined the leadership for HAL and Princess under Jan Swartz, who was the president of Princess. She is now Group President of Holland America Group, and the president of Princess, John Padgett, reports to her. Since she was the president of Princess during what I consider a major downhill run, I wonder if the same is in store for HAL.
I also sail Viking and Oceania. It is certainly a different experience on their ships, but due to the major differences in price points, I don't try to compare. In fact, my next cruise in 70 days is a 39-day Viking Ocean cruise. To correct some misinformation -- if you regularly cruise Viking you can negotiate a 6-month pre-pay even if you book out 2 years.
I've also sailed with Celebrity and Carnival. Am still open-minded about Celebrity. Carnival (the short cruises) is fine for the party animals but I'm far past those days now. Good wine, good food, good music, a spacious cabin, and good balcony chairs is all I need these days along with my sweet hubby who will go with me on any cruise I come up with.