I took the JAL flight on the 787 from Tokyo to Boston earlier this month. I booked through American (my departure flight was JAL9 out of ORD) who I guess has a codeshare agreement with JAL. I was originally supposed to return from Tokyo on AA154 (equipment change at ORD) but I called and for not so much more, I was able to switch my flight to the non-stop. Just figured I'd share my overall impressions of the experience:
Aircraft:
I flew a JAL 777-300 over there from Chicago so I have a good reference point for comparisons. The 787 is neat looking and very distinct from the outside. Narita has two nice outdoor obvservation decks and the JAL 787 was the only one I saw (ANA has a few but I didn't see any). I was also hoping to see an A380 (LH flies one to Narita), but no luck either. The windows are noticeably larger than other large commercial aircraft. I wasn't at a window seat so I didn't really get a chance to play with them. The cabin was nice, but there was little difference between the economy seats on the 787 than on the 777. Maybe a LITTLE more legroom on the 787, but not much (JAL doesn't give you much to work with there). The cabin pressurization is supposedly different in the 787. Didn't notice much difference, but I tend to do well with keeping hydrated anyway. The lighting was pleasant, but not groundbreaking. Virgin America uses it on their A320s. Cabin noise was slightly lower.
Overall, the 787 was neat, but I would hardly call it a novelty. I'd imagine that anyone who wasn't into aviation at all wouldn't be able to tell that that much is different about it. JAL still hypes it up (They have 787 post cards for all the passengers), but there's not TOO much for the passenger to notice. The real difference is in the technology, I guess.
One thing I like about JAL (whom I've never flown before): They're really laxed with the seatbelt sign. It went off about 2-4 minutes after take off and didn't come back on until we were on final. This was the case both ways. It makes a 12 hour flight much more manageable when you know you can move at any time.