How others will see it. This classy but sometimes erotic post-Victorian story will appeal principally to educated women, although educated men and uneducated women might also appreciate it. This film helped cement Carter's reputation as a prestige picture movie star, at least until she aged out of the best roles.
How I felt about it. The casting and direction are fine, but the film's major asset is its script. The script is excellent. Sins are suggested and confirmed in subtle nuances of phrasing. There are no shouting matches or casting blame. The closest thing to a scene is Lord Mark's drunken pass at Kate, which is of less shock to her than his revelation concerning Millie.
Of our romantic trio, Millie is the easiest to understand. She wants experiences and love (and distraction) before the end comes. She likes Kate and Merton, partly because they are close to her in age, and partly due to Merton's charm, but also because they are working class in spirit. Millie has more interest in Venice than London, not because of its cultural and romantic advantages, but because she has little interest in blue-bloods.
Kate is more complex. She wants Merton, of course, but she knows the importance and benefits of money. She's seen what the lack of money did to her own parents. She feels bad about using or manipulating others, but she knows she'll get over it, if she gets what she wants.
Merton is the puzzle piece that doesn't quite fit. He loves Kate for who she is, and he doesn't want money that would (or would not) come with her. Yet, he's willing to use an older woman to get a party invitation to see Kate, and he's willing to play the role (despite brief complaints) of lover to Millie. His muckraking career is also abandoned too readily, since his passion would commit him to it.
Millie is actually a better person than Kate or Merton, although her wealth and declining health does make it easier to be herself. Merton is the man who attests to being completely ethical, but finds it impossible to be so in practice.
The most preposterous character is Lord Mark. This is a man who invites Millie to her estate with the intention of proposing marriage. But he's constantly drunk, and he wakes up his guests shooting at defenseless animals. Then he makes a pass at Kate, when it seems certain she will report his actions to Millie. In other words, his character in no way resembles an actual person. He's there simply to facilitate the interactions of our three leads.