Comparison with a land-based holiday
The advantages of a good cruise compared with a land holiday are that you get a comfortable, well-equipped room (not an antique with creaky floorboards, sagging bed, and wonky bathroom), you get more facilities outside the room than the normal hotel would provide, and you get to keep the same hotel and the same room while visiting a number of different places. When I think of some of my travelling holidays, packing and unpacking, searching for a new hotel every night, I can say that the cruise is definitely easier and more pleasant in this respect.
The funny thing is that we possibly enjoyed the days at sea best! It was relaxing to have nothing we had to do all day, and somehow sitting in a ship with the sea going past feels better than sitting in an equivalent stationary hotel. Firstly, it feels as though something is happening: we're travelling, we're going somewhere. Secondly, in a hotel we might feel guilty just sitting around, but in a ship in the middle of the ocean we can't get off the ship, so we don't feel guilty about it.
On a land-based holiday, you may have to do your own driving, which can be tiring. However, as we found, a long flight before and after a cruise is also tiring.
The main advantage of a land-based holiday is that you have much more flexibility. You can go where you like and do what you like, when you like (if you're travelling by car and not on a package holiday). You can eat each meal in a different restaurant; or buy food in shops and picnic. You can take more time for sightseeing or shopping.