TL;DR Version: Perfect casting, perfect execution. Probably rich with anachronisms for the sake of presentation, but those things won't register much in light of a job well done.
The Long Version: ..A Review Effusive with Praise
There can be no more scathing indictment on humanity than the fact that the BBC version of Sense & Sensibility is rated higher than this PERFECT adaptation of Austen's novella, Lady Susan. What are you people on? Reviews that are based on a desire to ride your moral high horse as opposed to reviewing the actual movie are absurd, unhelpful, and not worth considering.
For those who haven't read it, Jane Austen's novella Lady Susan is a depiction of a recently widowed woman in Victorian England with no fortune, using everything in her power to advance her own safety and comfort. She isn't very uh... "honest" about it, but before you judge her too harshly, remember that seduction was the only power women of the gentry could wield to advance or sustain their position in society. This is not your usual novel and the story is told through a series of letters from one character to another.
Since Lady Susan was written as a series of letters, the makers of this film had to do a lot of work translating first-person monologues into a standard format movie. They have done a brilliant job. I would send thank you letters to the screenwriters if I could. I have seldom seen a better translation of the style, energy, and soul of a book into a visual format. Only the 1995 version of Pride and Prejudice with Colin Firth and Jennifer Ehle does a better job, and that's because it was done as a series. They had more time to flesh things out and a bigger budget to do it. And considering Love & Friendship isn't a series, the creators did a remarkable job bringing Austen's complex and subtle characters to life.
What you see here is a perfect adaptation of book to film.
The casting is perfect. The costuming is beautiful, as is the scenery. Chloe Sevigny and Kate Beckinsale have excellent chemistry and are delightfully diabolical as Lady Susan and Alicia Johnson. It is everything I could ever hope for in a movie. The only short-coming is that Stephen Fry as the respectable Mr. Johnson doesn't get much screen time. Granted, it's in line with what is available from the source material, but it's the only thing I could think of.