NCL does seem to get more negative reviews in proportion to passengers carried it "seems".
I think it's like comparing Hotel chains, Days Inn is not going to compare to Mariott in a lot of areas, but neither is the Mariott going to compare to the Ritz-Carlton. For grins I quickly went on the websites for Princess and NCL. A 7 night eastern caribbean cruise on Princess goes for $679 for an inside cabin and the 7 night NCL itinerary goes for $479. In addition to price each cruise line has developed its own personality and each tries to attract certain demographics.
I'm a complete neophyte when it comes to cruising (well, my cruises were all on large ships with guns in my prior life) and my wife and I have been on 1 weekend cruise. Initially I was drawn to RCCL but went with NCL first because of itinerary choices, cost, departure ports and I'm kind of a "whatever" type person, so freestyle cruising seemed intruiging.
The thing I've noticed is that a lot of NCL's negative reviews seem to be written by those with a lot of experience on another line. While this is a natural thing to do it can maybe a little misleading to someone that's never cruised (that line) before.
Anyway, my personal goal is to have as many cruises under my belt someday as Sonny V or Richard and Mary or anyone else that has more than, like, two. I'd also like to have at least one sailing on each cruise line.