Research will tell you that Spirit was built in 1996 and updated in 2017. Don't be fooled...this is an old ship. Public spaces are very dated and balcony staterooms are painfully small. There were random odors around the ship, including (as reported by fellow cruisers) in some of the cabins. Our cabin had bedbugs. There are almost no places to enjoy a cocktail with a view of a window other than in one large lounge...and this same spot got quite old after a couple of days. Seating in the buffet is woefully undersized to support the pre-excursion breakfast rush. Food may have been the closest thing to a highlight. While the buffet was unimaginative and very average, the main dining room meals were perfectly passable and specialty dining options were quite good. A reasonably creditable wine list was tempered by a cranky beverage package. On board entertainment - again with some exceptions - could best be described as average, and in some cases was pretty weak. As a minor complaint, it helps if Trivia contests are hosted by people with a better command of the English language...
There were more problems with NCL. The crew on Spirit - while there were many great exceptions - was, on average, uninformed, unfriendly and uncooperative. On board communications were less than clear, which mirrored a problem with confusion and inaccuracies on NCL's website.
So my net....a 15 day cruise on Spirit was not necessarily a "bad" experience, it just was not nearly so "good" and exprience as we are familiar with on the two other lines that we know well.
small, particularly the bathroom. closet space was good and under the bed storage of luggage was helpful.