We're using NCL Air for the first time on our cruise from Reykjavik to Southampton (6/13 on the Prima). I was pleasantly surprised by the flights. We have a nonstop from Denver to Reykjavik with 1 checked bag each and seat selection included (Icelandair). Coming home, we have one stop in Miami; 1 checked bag each and seat selection were included as well (American). The only downside is that flying through Miami means we get back to Denver at 11:49PM.
We used NCL Air after pricing flights on our own and it saved us money this time.