I've been on numerous cruises with several cruise lines, including a 16-day transatlantic on the Norwegian Star and Caribbean cruises on the Norwegian Star and the Norwegian Spirit, which I enjoyed very much, so I was shocked by the Epic. Some examples:
Entertainment:
There were only 2 main-stage productions + a birthday-party-level magician and a third-rate hypnotist for the entire 13 nights. When I complained about the lack of entertainment to guest services, I was told: "You need to get a hobby so you don't have to depend on others to entertain you."
Cabin was smaller than on other cruise ships, but very efficiently designed, with more than enough storage space.