Sets and Costumes: Superb!
Screenplay: (pained face...) Well, it was charming. British TV science fiction shows are charming too. But the screenplay simply wasn't that wonderful.
Screenplays adapted from history have one fatal flaw: everyone knows what's going to happen. The Titanic is going to [SPOILER] sink. [END SPOILER] And if you know the story of King George VI, you know what's going to happen. The time not spent on suspense is spent noticing how they choose to manipulate history.
For example, Edward VIII abdicates a few weeks before Christmas, and they suggest in the film that George VI doesn't even attempt to give a Christmas broadcast. Instead, his first big speech rallies the British at the start of WWII. But of course he gave a broadcast. They skipped it, because that wouldn't have been good cinema, and if I didn't know better I'd never have guessed. But since I do know better ... it jumps out as manipulation.
And little details were jarring too. If you know that Wallis Simpson had a "wen," a mole on the side of her face ...
You look for that mole, and when [SPOILER] it isn't there [END SPOILER] you wonder why the decision was made to de-mole her.
Imagine if it's 2020, and you see a movie of the Clinton-Lewinski affair. Let's say they give Monica Lewinski blond streaks in her hair and set it up so the impeachment trial occurs while the Clintons are vacationing in Cape Cod. You couldn't get caught up in it because you'd compare reality with drama and question every difference.
And finally, I was distracted because I kept wondering what the Royal Family thinks of this movie. Probably, "As if Grandpapa would ever [SPOILER] be friends with a commoner! [END SPOILER] Quite!"