I flew the 787-9 on Friday in J. The J cabin was relatively small, though the seat is superior to the standard LH offering thanks to the 1-2-1 configuration. Entertainment system appeared to be the same one you get on their other long-haul aircraft.

Y had Premium Economy and for some reason no one was allowed to sit behind row 30.

J class service was a quick snack basket with a cucumber sandwich, granola bar and apple. Not bad for a 30-minute wide-body flight.

As an aside, I feel like 75% of the J cabin was on the flight as an enthusiast. Many taking photos, filming, talking with the crew.