If you actually manage to get onto a flight that has not changed or been cancelled then well done !! The service onboard is one of the best in the air.
HOWEVER.... if you are one of the countless victims of JAL's flight changing / cancellations (or worse, you need to contact the call center) then it is one of the worst customer experience you will have.
I had flights to Tokyo and then a domestic connection within Japan. Out of the blue I receive an unclear email that states the flights have changed, the departure time and date are the same but the arrival times (on a direct flight) have changed and the connections are now misaligned leaving me stuck. The website was not functioning properly and so I was forced to call the call centre during the slim daily window in which they operate. This is where the issues started... nobody EVER answers,
Unfortunately due to the fact that I had a meeting I had to abandon my attempt and getting any information after a mere 90 minutes in the call center queue, listening to the same loop of music and the same condescending voice "All of our agents are busy, please wait for the next available agent or call back later" - the really galling part is every so often I hear a beep on the line where somebody is there but not answering.
Even though I travel to Japan regularly I will really think long and hard before ever choosing JAL again, they really have let themselves down with their appalling customer service, no callback service, no estimated wait time NOTHING...