No I've not had a bad experience before, and I always use the Wi-Fi on JAL international. It's a big reason why I fly them. I like that you can use multiple devices, even if not concurrently, without paying again (which is the case with ANA). I also fly CX a lot who use the same Panasonic system and haven't had any issues with them either (the GoGo system on CXs 777s on the other hand... try that if you really want a bad experience!).

In regards to MFA, this is always difficult on aeroplanes but I wouldn't think it much the fault of the airline. If you need to authenticate next time, make a second Panasonic account and purchase a 1 hour pass for your phone so you can approve the requests - if work is the goal then a few extra dollars saves the pain. I'm not aware of any airlines with a paid wi-fi service that allow multiple concurrently connected devices.