War Horse: another Spielberg classic

Yesterday I was given the choice of going to see the Maggie Thatcher film or War Horse. I chose War Horse. Good choice. Spielberg has woven so many threads into a really powerful and moving story of a boy and his horse. There is huge scope for follow-ons and sequels,  although I hope none are made. Much better to leave much unsaid. I don’t know if Michael Morpurgo has written any of those other stories,  I guess I should find out.  Either way, I enjoyed the film, and would like to see it again, I have the impression I missed some subtleties.