Edward's persisting in the engagement is portrayed as the honorable thing to do. However, the modern reader can't help noticing that Edward's stance would lead him to a life-bonding contract with an individual he no longer cared about. The engagement is also technically void (made by two minors without their parents' consent), meaning it's not legally binding; Edward sticks to it because he feels morally bound. With that said, Edward's breaking off the engagement after its reveal would have ruined Lucy's reputation and destroyed her chance of ever marrying, let alone marrying well. Given her financial situation, that would be a sentence to ruin. Only women in the Regency era could break off an engagement, and even then it was a risk; Lucy only got away with it because she married Robert immediately thereafter.
Girls are considered able to marry much younger than in modern times. When sixteen-year-old Marianne objects that Colonel Brandon (35) is old enough to be her father, this is treated as a sign of her immaturity. Her own mother later says that it's better to marry an older man whose character and position in the world are fixed. (There's also the fact that Brandon is attracted to her because she resembles his Lost Lenore whom he knew since they were kids and fell in love as teenagers.) Willoughby's crime of impregnating and abandoning Eliza condemns him, but not the fact that she's even younger than Marianne.
Wangst: Deliberate — Marianne's response to her romantic woes begins to take on this edge, which to her credit she eventually comes to realize.
Awesome Music: Patrick Doyle's soundtrack, especially the main theme, which is reprised multiple times and comes to a spectacular crescendo in the wedding scene.
Faux Symbolism: On the commentary, Emma Thompson praises the symbolism of Brandon giving Marianne a knife to gather reeds with. She cheerfully goes on that she doesn't know what it symbolizes, it's just good symbolism.
Watch Imelda Staunton (Mrs. Palmer) interact with Emma Thompson in this film, then follow it by watching their characters interact in Harry Potter and the Order of the Phoenix. You might never look at Dolores Umbridge and Sybil Trelawney the same.
Hugh Grant and Emma Thompson play siblings in Love Actually. Emma Thompson is also married to Alan Rickman in the same movie. And if you count a brief clip from Titanic (1997), even Kate Winslet appears in the film.
Jerkass Woobie: Although Lucy Steele is possessive, selfish, and full of Sugary Malice, there are several subtle indications in the film that she's even worse off than the Dashwood girls. Her clothing isn't as nice, when Fanny kicks her out she ends up alone on Mrs. Jennings' doorstep crying to be let in, and she has no other connection by which she could find a man to marry. Her treatment of Elinor is still wrong, but it's somewhat understandable.
Moment of Awesome: Emma Thompson's Best Adapted Screenplay win makes her the only person to have won Academy Awards for both writing and acting. (She got Best Actress for Howard's End.)
Signature Scene: Colonel Brandon carrying Marianne back to the house after she goes walking in a rainstorm is so iconic that someone complimented Emma Thompson for depicting that scene from the novel so well, and the 2008 miniseries reproduced it with only slight modifications. In fact, this scene originated with the film itself.
Values Dissonance: In the movie, Colonel Brandon was forbidden from marrying his cousin Elizabeth because she had no money. In the book, she was forced to marry his brother specifically because she did have money - and it had to stay with the oldest son to keep it in the family.
Tough Act to Follow: The series had a challenge to be remarkable in the face of an Oscar-winning film starring the likes of Emma Thompson and Alan Rickman. Andrew Davies said one of his goals was to make viewers forget about the movie while they were watching the series, and Hattie Morahan (Elinor) chose not to watch it so she wouldn't have Thompson's performance in her head. Critical reception mostly praised the adaptation as strong in its own right, but occasionally tended towards descriptions like "nothing glaringly wrong" or a good companion adaptation to Lee's. (It didn't help that certain aspects, like Edward and Elinor bonding over Margaret, Brandon's flowers versus Willoughby'snote albeit they're strawberries here, and Marianne collapsing in a rainstorm are taken from the film rather than the book itself.)