People's expectations of a cruise vary so widely that I can see why reviews of the same voyage or cruise line make you wonder if you were actually on the same ship!
1) People who board with a negative attitude do not lose it at sea ... in fact, it gets worse as time goes by.
2) People who expect the cruise to be "all about them" and that their every whim should be catered to should rent a yacht not go on a cruise.
3) People who do not like lines should not go to the restaurant at peak times nor try to be the first off the ship in ports nor wait for an elevator.
4) People who do not like hot weather should not cruise to the Caribbean... (Or if they dislike the cold, sail to Alaska).
New or old, the cruisers I meet who embrace each day as a new adventure really have a great time in spite of weather food cabin size etc.