We got this as part of a package tour to Ireland. This is a budget airline with all that entails (or doesn't!). Just look at the lengthy reviews(rants?) here. If you don't mind the inconvenience and complete lack of creature comforts, then you're good to go here. Really. This might even be the future of travel.
Otherwise, save yourself some pain and book with a major carrier and get the best seat you can afford without crashing your travel budget. We will. The carrier is clearly not for people like us.
A 6 hour flight and they don't give you water unless you buy it! Wow! I remember a few years ago being admonished by a flight attendant on how important it is to drink
water during a long flight. How times have changed! So, bring water with you or plan to buy onboard.
Same goes for food, although our tour arranged for meals for our group, and it was just fine.
A particularly painful thing for me was that the seats barely recline, so you're sitting fairly straight up for 6 hours. My bad back didn't like that, but I planned ahead with pain meds and a neck pillow. An additional lumbar pillow and seat cushion would also have helped me, so maybe others would also appreciate the suggestion.
I'd never flown with Norwegian, and won't again, but if you're young and healthy and on a limited budget (and traveling light---very light) I don't see you having a problem.