The problem is that there are so many different types of cruises, but, judging by reponses here, including my own, we are all giving our views on cruises in big ships with lots of entertainment and facilities.
But when I think about it, I have actually been on 4 cruises but each totally different from the other. The first was on the Nile, and the ship was pure Agatha Christie, built during WW1 with about 30 cabins. Then we went on a winter cruise up the Norwegian coast and into the Arctic circle. The Hurtigtuten ships were still effectively ferries with cabins like glorified Brittany Ferrries cabins, no entertainment or leisure facilities except lounges with huge windows and all meals were at a fixed time but all buffet, so we could eat as much as we wanted of really good freshly prepared and cooked food. Then there was the classic cruiser which was definitely my least favourite. Then we did a German rivers cruise, entirely different again. Mooring up in the centres of towns and having all day to explore them on our own or with a tour.
The question, however, was about living your life on a cruiser, and to be fair, you would not live permanently on a river cruiser, Nile or Rhine, or even a cruiser going up and down the Norwegian coast, week after week,