Norwegian is not a bad choice if you have plenty of time to get from point A to point B and are not making any connecting flights. They seem to be a reasonably priced, no-frills airline. However, if you are making any connecting flights, DO NOT fly Norwegian! EVER! Their policies around replacement tickets are absolutely inflexible. Your savings will quickly evaporate if your connecting flight is delayed, as they will make you purchase new tickets. For a family of 4, we were going to save about $120 by choosing Norwegian over SAS. However, because our flight into Arlanda was delayed (and we cold not contact Norwegian because we were in the air), it ended up costing us over $1000.00 extra.
ARN-UME and ARN-TLN (separate trips). FlyNordic is a nice low cost airline, with very good fares. The legroom is quite generous (I'd guess at around 34 inches of pitch), and the food available for purchase is perfectly acceptable. The staff was friendly with our 13 month old, and the flights were on time. The biggest downside was that the line at check-in was very long for both flights.
Copenhagen to Stockholm-Arlanda. I was quite surprised to find self- service check-in machines in Copenhagen; in fact FlyNordic shares them with KLM and Sterling. Otherwise the queue at the check-in desk was terrible, as there was only one counter open. Flight was delayed by one hour and this could have been announced much earlier. No seat assignment, meaning that everyone wanted to board first. But I have to give bonus points to the cabin crew: helpful and smiling throughout the entire flight.