I do both land vacations and cruises. With a land vacation, I have to figure out hotels, car rentals, restaurants, what I want to see, flights, etc. It can be a lot of work. With a cruise, I have to figure out where I want to go, how to get to the port, and that's about it. The second I set foot on the ship, I don't have to do anything but relax. I do all my excursion planning ahead of time (I don't usually book through the ship), and it's very stress-free. You unpack one time, and you wake up somewhere new every day. I've been on 16, and usually go with Celebrity as there are fewer kids, better food, and the overall quality is better than I've experienced on RCL, Carnival and NCL.
In my experience, people who complain about cruises have either never been on one, have only experienced a short "booze cruise" or can't afford it. I'm diabetic, and I find it very easy to eat in a healthy manner on Celebrity. I usually lose a few pounds when I cruise because I don't overeat, and I get a lot of exercise.
I typically do 4 weeks of vacation a year, 2 weeks cruising, and 2 weeks on land. When we go on land vacations, we usually book a hotel for the first and last nights, and make the rest of it up as we go along. It's a very different experience from cruising, but I enjoy both.