There were many people who should really not have been on this cruise. I think the ship is not designed for the unfit or the very elderly. Because it was particularly rough at sea, we talked to passengers who ended up with broken ribs, broken leg (broken while on an shore excursion)which ruined the rest of his cruise and in Amsterdam the emergency services were called to a passenger but we didn't find out what had happened. We saw people in wheelchairs and zimmer frames when it is obvious the ship is just not designed for it.
We were fairly mobile but even so it was a nightmare getting up and down between the decks when lifts were constantly out of action or too slow. Also, watch your spending on these 'cashless' cruises. Everything is paid for using your cruise-card and you pay at the end of the cruise. As the ship is basically a floating bar/hotel, it can easily mount up. Beware.
The good news.
The food was wonderful and plentiful (although some people felt the need to complain). The staff generally were very good particularly in the Waldorf Restaurant (the self-service 'bistro' tended to get very crowded). Shows and the on-board entertainment were good and were needed because of the lengthy time at sea. We were on the lower 'Caribic' deck, just above the waterline, so in rough seas the portholes were clamped shut. The cabins were very clean and easily large enough for the two of us.