My wife and I just returned from a 7 day cruise on the Jewel. What a great experience! First let me say that we have sailed on Carnival and Royal many times, but this was our first experience with Norwegian. I will begin by saying that unlike some who post, I have never been on a cruise I hated. In my mind even a not so great trip is still better than a week at work. With that said, I will outline some of the differences I noticed.
First of all the ship appears to accommodate fewer passengers for its size than some other ships we have been on. That gave us the feeling of a bit more space in the public areas. As with most ships the rooms are a bit on the small side. The bathrooms however are designed with one feature that should be standard on all ships. It has a sliding glass door. That may seem like a small thing but on other ships we have been on they have a small curtain. It almost always allows water all over the floor.
We booked at the last possible minute. Literally 7 days prior to sailing. Because of this we didn't have much choice on room selection. We were assigned to deck 8 mid ship. We were concerned because the public spaces were directly below. After looking on a map of the ship we determined we were directly above the Karaoke room. We had absolutely no issue with noise. The bonus of deck 8 was that the 24 hour restaurant was located on that floor. This made it super convenient to slip over and get a cup of coffee or snack without schlepping all over the ship. This is something to consider if you like to keep late hours. By the way, the 24 hour restaurant is the the best kept secret on the ship. I think most passengers don't even realize its there. There is almost never a wait to be seated.