It’s interesting how the same novel can give rise to multiple screen adaptations that are strikingly different in tone and their approach to the characters. Neither of them is really like the novel either, because you’re not going to capture the experience of reading Austen in a screen adaptation.
Overall, I prefer the 2009 Emma, but there were things I liked about the 2020 one too. I haven’t watched either of them recently, so I’m working from memory here.
In both versions, Emma is conscious of her social rank and needs to become more mature, considerate, and perceptive. The 2009 version brings out something a little vulnerable and lost in her, connected to the fact that she’s led a sheltered life and seen little of the world; also, the acting is more informal in that one, so her mannerisms come across as younger and even childish sometimes. In the 2020 one, she’s steelier and more sophisticated (even though her readings of social situations can be wildly inaccurate, which is part of the humor).
The 2009 version has beautiful pastoral imagery, and the interiors are both grand and soft; they have an earthy palette, lovely furnishings, and a lived-in feel. The 2020 version takes grandeur to another level. The interiors look pristine and lavish. Emma and the other characters are like dolls in a bejeweled dollhouse. This also fits the sense of Emma living in a bubble; nothing exists in the world outside of the dollhouse. (There are similar differences in the outfits – the 2009 adaptation gives Emma some lovely gowns, but the 2020 one takes the fashion to a whole other level.)
The 2020 one plays up the social comedy more, especially with the introduction of the quiet, long-suffering servants who try to iron out every inconvenience in the lives of the wealthy people having fits of drama around them. (The servants’ facial expressions subtly reveal what they dare not say.)
As for Knightley… overall, I prefer the 2009 one (Jonny Lee Miller), but Johnny Flynn was also good in the 2020 adaptation. I think each Knightley is a good Knightley for the adaptation he’s in.
The 2009 Emma is a mini-series, which makes it feel more expansive and gives the scenes more breathing room. The 2020 one is a regular movie, more constrained in time with a faster pace, and so the humor also has a more staccato feel.
Watching different Austen adaptations is an interesting way to study filmmakers’ choices. What do they try to emphasize from the books? How do they try to communicate a different social world to a modern audience, or bring out a novel’s humor (which in some scenes comes down to a turn of phrase or an ironic tone)? If you’ve watched either of these, share your own opinions on what worked for you.