I travel the London to Amman route every month. The 787 in J is a very competative product. The seat and IFE are very good. I have always found the crew very attentive and the 5.5 hour flight goes very quickly.
Now here is the kicker, while your itinerary may say 787, I have only flown on it once in the last six months. The rest of the time the aircraft is changed to the A321 or A330 about two weeks before the flight. In these aircraft the j is very tired.