Not really what I was expecting, and different than standard Nolan. Grim. I was unsurprised by the use of Elgar's "Nimrod". My favourite bits were the external shots of Spitfires. Wonderful machines!
Wow! What a diversity of personality, despite the (fairly) narrow range of backgrounds of the children. For example, the lack of ethnic diversity. As Michael said - the trio of London public school boys show really quite surprising variety. And what a change, for some of them, since 7! I expect the next episode to show a similarly huge change, by age 21.