One of the best reasons for me to cruise with NCL is that they aren´t as pushy about how much you can do on their ships as some other conpanies. Look in an RCCL-broschure, they only talk about all the things you can do on the ship. Cruising for me is more about doing nothing or as little as possible, at least when I´m on the ship!
Of course i don´t have to do everything on the ship if I should cruise with RCCL but the broschure gives a good idea on which people they want to attract and that´s not me!
I know that there are cruisecompanies with higher standard than NCL bur in my european view of it the big ones are NCL and RCCL and my opinion is that NCL is more for those who really know what they want. If you don´t know what you want and go to a travel agency in Sweden and ask for a cruise, they will sell you an RCCL-cruise! That´s a fact because most travel agencys in Sweden don´t sell NCL-cruises themself, to sell that they need to contact an specialist (mostly Swanson´s I guess).
I know what I want and that´s NCL! I also think that their itineraries are much better than RCCLs.
Another big advantage is NCLs broschures. Look in RCCLs, almost no prices at all. NCL have a lots of prices in the broschure. I know that the prices aren´t always correct since they changes all the time but at least they give a hint how much the cruise will cost.