I am half of an "older couple," but active. Usually we cruise Celebrity and have cruised Carnival 2 or 3 times for specific reasons (Country Music Cruise). We had heard good things about Princess; found a week-long cruise for a good price, and invited another couple to join us on the trip.
Our stops were Roatan, Belize, and Cozumel. That trip was supposed to have had a fourth port (the Maya Riviera), but there were too many ships stopping at the port. So, that port never actually showed on the itinerary. What we experienced was that because there were SO MANY ships stopping at the remaining ports, often those ports of call were somewhat overloaded with cruise tourists.
We booked too late to get a choice of evening dining times; so often had a bit of a wait to get the mediocre meal (I'm attempting to be generous with my judgment of the food). "In a nutshell," the food was overcooked and under-seasoned. For example, I asked for my steak to be VERY RARE ("cold on the inside, please"). It came back medium. The waiter got me another huge chunk of meat to replace it... medium. My friend loves Eggs Benedict: the yolks were completely dry... like a hard-boiled egg (only with some sort of packaged topping). One night I ordered a Thai dish... completely BLAND! (When we asked for some "chili sauce" and they brought us Tabasco!)
Another time we ate at the British pub (forgot its name).... Neither the Steak and Kidney pie nor the Fish-n-Chips were at all authentic (soggy and without flavor).
The overall feeling of the ship was crowded: not enough seating around the pools; $15 or $20/day if you wanted to have access to the "Sanctuary" (a quiet pool). At mealtime, the buffets were always crowded, with many food choices, but the food there was also poorly seasoned.
Cabin: the attendant was slow to respond; nothing special done to our cabins as on other cruise lines (like the little wash cloths made into bunnies or elephants). Had to be asked for ice; no automatic pitcher of ice water kept in the cabin. (In fact, I'm not sure I recall having had a pitcher in the room... only an ice bucket that was kept in the fridge).
I did not find the entertainment particularly entertaining. The best night - in my opinion - was the one in which the crew performed. Toward the end of the cruise, the entertainment line-up changed: the "old" singers and dancers left the ship; a "new" entourage boarded. The new group had pretty costumes. Period.
I have NEVER been critical of a cruise. If this cruise is typical of Princess Lines, I cannot understand how they got their reputation. From my memory of cruising Carnival, the Crown Princess had worse food... but fewer kids onboard.