How did you find Norwegian long haul?
No worse than any other trans-Atlantic economy flight I've done and much better than United or Aer Lingus out of BHX. The trump card for Norwegian is the Dreamliners. The leg room, seat width and noise levels are far better than other carriers' older birds. We did the one up from basic tickets where you get fed and get hold luggage. The food was again, no worse than any other and better than some. They also serve alcohol with the meals, unlike the tight b@stards on United.
My only observation is that they depart a bit later than some other flights I've done. So we were absolutely ruined when we got there (about 1900 US time meaning at the hotel by 2200 earliest). But on the way back, taking off at 21.30 meant we got a full day in before going to the airport, and landing mid-morning meant no rush hour to deal with.
On the whole, I'd thoroughly recommend them, especially when you look at their prices!