Just my personal observations:

(1) Meal quality is certainly declining - meals from the USA are known to be bad but now it's even worse, especially the cold "Lox & Bagel" for the second meal for a 14 hour flight (I was shocked!!!); there are also very limited snack options between meals; no hot towers on most flights for economy (has anyone else also observed this?)
(2) For economy, JAL crews used to do regular drink runs in between meals during long haul flights - this no longer exists.
(3) Sky Wider is as usual great - however, the seats are very hard and start to shown a lot of wear and tear
(4) Delay is becoming more usual than before
(5) Crew service has become inconsistent - funny enough, I've found service of overseas crews of JAL (especially those from Hong Kong, Bangkok and Taipei) to be consistently better than the Japanese crews; I've met a super impolite Japanese economy class supervisor on my NRT-MEL flight in April this year that ruined the entire experience (this is the first time I saw a very lazy JAL cabin attendant (and a supervisor) who bowed towards the back of the passengers, did not check overhead compartment, only knew how to order other crews to work for her and was super annoyed when passengers ask for more drinks)
(6) JAL is still better than others in terms of overall experience I would say but the gap is narrowing (and potentially not worth the price difference).