I flew them this week. JFK to OSL return. The worst bit about the whole trip was JFK. Literally a hole I never wish to revisit. But the Norwegian experience was actually awesome. Low fare on the way out and premium (bid to upgrade) on the return. 787 900 place is fab, crew were great. Honestly no different than any other flights I have taken.
I have a couple of other trips booked with them, hope they stay afloat!