We ended up on this particular cruise when it was chosen by family for a get-together/celebration. Positives: cabin was comfortable, but daily cleaning was often very late (like 5pm) which can be rather inconvenient and items within our cabin were never re-stocked (mini-bar, teas, coffees, etc). One has to assume that the stewards have too many cabins to clean each day. Food was very good considering the mass catering.
Negatives: Being ripped off for amenities one should reasonably expect when staying as a 'guest'. For example, an 18% gratuity levied on everything + a 13.5 Euros per day, per customer 'service charge'. For goodness sake, Norwegian, stop hiding these charges unti people are on board and 'captive'.
Lastly, and these were the killer blows for us: We have to work online, 365 days per year as we own our own small hotel and must therefore have access to email and our online reservation system. Upon embarking, we checked the internet provision: either we took the 60 minutes or 200 minutes for $75 or $125 USD, or at $200 USD, an 'UNLIMITED 7 DAY' package. We were worried about not being able to answer our business queries, so we went for the 7 day package. Internet service was sporadic and unreliable but we accepted that as it is satellite-based being at sea on and off.
Comfortable, but cleaning service would not have passed a normal hotel service.