NCL's entertainment is excellent. With the advent of Freestyle 2.0 they have retooled their entertainment as well, with some of the shows being held twice during the cruise, in case you were dining and missed one.
They have a pool side bar-b-q, that's a deck party, after almost every port visit.
There's a mix of choices in what they call NCL U, which includes martini mixing, tequila wasting (watch out), and beer tastings. They also have several fun events including interactive seminars with the Second City Comedy Troupe.
A bit hit in the Spinnaker Lounges is their big White Hot Night Party, and there's also a Monte Carlo party in the casino one night.
LOTS of entertainment options, if you choose to partake. No way to get bored if you're looking for fun.