Here is my 2 cents. I have 2 disability scooters. Afikim S4! And a smsrtscoot. Opposite ends of the scooter world. The AFIKIM is amazing with a range of 30 miles, 10mph. Not portable in any sense of that word. Would not work on a cruise ship. The smartScoot costs mid 2k. It weighs about 40lbs with the seat. It costs 250 to 400 dollars on average for a cruise scooter rental. 10 cruises it pays for itself. I have literally been all over Rome on mine. The Coliseum, Forum, the Vatican, all over the city. There were zero problems.
As far as anyone choosing one, that is a very very individual question. Why do you want one? Does it fit you? Do you feel safe on it? How fast and far will it go. 4mph is ok on a ship! But when touring it might be too slow! Being a big person, I was 350 lbs, I was concerned by construction.
Go to a scooter store, try them, inside and outdoors. Do you like 3wheels or 4? Do you feel safe on it? Will it hold a cane or 2 or crutches?
HTH