We have sailed on NCL three times over the past 3 yrs, and while we have enjoyed it enough to return, we can see things declining. This is not a negative review because honestly we have enjoyed sailing NCL, more so, it is an honest eval of the good with the bad.
Pros: The Dawn - we have sailed twice. It is a large, spacious, nicely laid out ship with many places to eat with great variety. There is a huge atrium, nice library, movie theater, excellent auditorium for shows, and various places to get out an about on the ship. The Dream was a bit smaller and due for a makeover, but still okay.
Freestyle dining we LOVE, but did hear many people complain too. It does take some getting used to. On our first cruise, the more seasoned cruisers knew to book all the prime dining hours in advance so we were left with eating at 5 or 9:30. They have since changed it so that everyone can only book reservations one night in advance which is much fairer. The gym and spa were over-the-top second to none! State of the art equipment in tasteful well spaced out gym overlooking the ocean with private TV on each piece of equipment.