I flew Melbourne to London and return and then back to London earlier this year on the 787, I thought it was an improvement on older gen airliners, and while I didn't notice any difference in humidity I must admit to feeling much fresher than usual afterwards, my only complaint was the seat cushion was hard and was digging into my legs after a few hours, mind you we were lucky to have 3 seats between 2 of us all he way round.