It's always the oddest little details that hit so well - the Doctor's sneakers and trouser legs getting wet in puddles he won't/can't avoid, acting like an eccentric uncle embarrassing people in public, Jack spending his (limitless) time learning new trades - and getting annoyed with the Doctor's unchanging face - and then there's the dialogue and that utterly perfect understated understanding... Nope - nothing constructive to add I'm afraid, just damn that's good.