Norweigan/Primera/Wow airlines

I can only speak for Norwegian Air Shuttle, however they are saving travelers incredible amounts of money from the upper East Coast, Florida and the West Coast. They are starting to service Mid America with limited flights in the near future as new airplane orders come online.
Only increased competition will force lower airfares from the legacy air carriers. Where there are no budget air carriers, Summer, 2018 airfares remain very high.
We have flown Norwegian 5 legs, and are flying back from Dublin next month on a brand new Boeing 737 Max to New York. We still need all the competition we can get to keep airfares reasonable.

Can only comment on Norwegian. Flew them from Denver to London last November. New planes, cabin crew was friendly, everything went well for the flight. Just be aware of luggage rules 10 kg limit for personal item and carryon combined (and they did weigh it at check in). Have to pay for seat selection (we didn't but our family was kept together), meals and any extra bags are more expensive at check in than prepaying online. We will fly them again as their prices were by far the best from Denver to London.

Edited from 20kg to 10kg thanks Frank for pointing this out.

Norwegian air's hand luggage combined limit is 10 kg (22 lbs) and not the previously state 20kg. I'm sure it's just a typo.

Zero for two on Norwegian. In January our daughter-in-law was to fly Newark to Rome for her semester abroad. Plane was cancelled as inbound flight was cancelled, she was not notified until on way to airport (from Philadelphia). Replacement plane brought in but flew them, 7 hours later on take-off - to Copenhagen, where she had to overnight and pay in advance (including her already paid luggage charge) for Norwegian to fly her to Rome a full day later, barely on time. At this point they are still waiting for the excess charges and EU 261 money, which was finally approved, to be sent to their bank.

Then last Friday, our son flew same flight to visit her for the week,. Or tried to, this flight was also cancelled,and they then shuttled him to JFK where 7 hours later a plane then left, but at least for Rome.

I would not trust Norwegian for a transatlantic flight.

My advice: ignore reviews (especially from a tiny sample size like this forum) and pick an airline whose itinerary and price fits your needs. I look for value and can tolerate a fair amount of risk (everyone has a different risk profile, so know yours and act accordingly). If something goes awry, just roll with it and keep an open/optimistic attitude ("this too shall pass"). An inconvenience is not the end of the world. Whenever I've been inconvenienced, I've gotten compensation and it was more than adequate. Most people have a totally mundane experience with these (and any) airlines - the only ones that furnish reports skew to the good/very good and bad/very bad.

Recent threads re: WOW

https://community.ricksteves.com/travel-forum/general-europe/wow-airlines-good-or-bad

https://community.ricksteves.com/travel-forum/packing/wow-air-personal-item

Flown both Norweigan and WOW with no issues. WOW was FCO to Iceland, and Norweigian from BOS RT and will do so again, probably this fall.

I've never flown any of them, but do be aware of the potential extra charges compared with other carriers. If you need or want advance seat selection, a checked bag, or onboard food, you have to pay for these (of course, the legacy carriers are starting to charge for seat selection too - it varies).

I was struck that for New York to London, Primera Air used Stansted, which is farther from London than Heathrow, but very close to Cambridge. So, if you use Primera Air, you can start or end in Cambridge very easily.

“do be aware of the potential extra charges compared with other carriers”

Even with extra charges, which you choose if you want them, WOW and Norwegian are still less expensive than other airlines (unless you get a screaming deal).

There is a general risk with airlines that are expanding from a very small base. These airlines have very small fleets, so if something goes wrong it can play havoc with the flight schedules. Also, the upstart airlines are experimenting with new routes all the time. For example, Norwegian started a flight last fall from my Bradley - Hartford (my home airport) to Edinburgh and cancelled it several months later.

I prefer Aerlingus for transatlantic travel.

I personally would not buy a ticket on Norwegian right now. This article discusses their creative accounting, big losses (while other airlines are doing quite well), and questionable sustainability as an airline. The last section of the article asks if the airline will survive the spring; happily for current ticket holders, the answer appears to be "yes."

Any experience specifically on Primera Air? (East coast to Europe)

Norwegian just started to fly direct Seattle to London. I haven't tried it yet. But it's so much cheaper than most of others that I can afford even hotel in London and still pay less. And then from London Stanstead by Ryan Air direct to Brno. Much cheaper than by Delta via Amsterdam to Prague and then by train to Brno. Train price is of course negligible.

I have 3 friends that have flown Norwegian many times, they all like it very much. Their prices are lower than other airlines for non-stop from west coast to Europe, even after you add on à la carte optional fees.