I had taken two cruises with Norwegian until I decided to cruise with Princess. It was a horrible experience. The service was so bad that one server literally refused to bring a slice of pizza to an old man. The cleanliness on the ship was so bad that everybody got sick. The activities were boring.
I absolutely loved my NCL experience before, and I couldn't believe how bad it could be! The ship had maintenance issues. The rooms weren't cleaned properly. We paid hundreds of dollars to join the spa during the cruise and instead of refilling the soap with soap, they kept topping it up with water. I would recommend avoiding this company at all costs. They actually had these breakfast biscuits that they kept re-baking for every morning because on every second day they were rock hard and darker in color.
I made a video to summarize my experience.