In reply to mav:
I saw the recent publicity about these flights as well.
The airport for NYC is in the Catskills. Apparently you can make it work very cheaply for you by making your holiday about the Catskills during the week when accommodation is cheap and then heading into NYC at the w/e when the hotels are cheaper there.
I've flown with Norwegian in Europe. No drama. Bit of bun fight on board as there was not enough space for all the carry on luggage and no volunteers to have their stuff put in the hold. Not much different than an Easyjet, Ryanair or BA flight really.