Here are my thoughts. WARNING: The following posts contains mild spoilers for the movie, and discussion of mature subject.
So, the movie begins pretty well, with the story of a teenage girl starting to experience her sexuality. She starts by having sex with a guy due to peer pressure, finds out its not for her, has lesbian fantasies, goes to a lesbian bar, meet Emma (the blue-haired girl), has to defend herself from her friends accusation's that she is having sex with Emma, etc. Basically, it's a bildungsroman, with a few pseudo-deep conversations about art strung throughout because, well, this is a French movie. For an hour and a half, all is well.
And then comes the scene. And what a scene. It's the sex scene. Here is what the writer of the original GN said about it:
Because – except for a few passages – this is all that it brings to my mind: a brutal and surgical display, exuberant and cold, of so-called lesbian sex, which turned into porn, and [made] me feel very ill at ease. Especially when, in the middle of a movie theatre, everyone was giggling.
"The heteronormative laughed because they don't understand it and find the scene ridiculous. The gay and queer people laughed because it's not convincing, and [they] found it ridiculous. And among the only people we didn't hear giggling were the potential guys [sic] too busy feasting their eyes on an incarnation of their fantasies on screen."
And sad to say, but I agree with her.* Those scenes are so over-the-top, they cross the line from eroticism right into porn. And everyone in the audience with me (mostly made of university student, including a few lesbian couples) did laugh. At the end of the movie, I was taking comments, and many people were too uncomfortable to talk to me. And those who did basically summed it up as "Not bad, except for the porn part"
So, after that 15 minutes where the movie stop to show a porn scene, what happens? More conversations, all shot in close-up so its hard to get a complete picture, including one really puzzling discussion about how the female orgasm is some mystic event much more important than a man's orgasm (wtf?), more short sex scenes, one good argument/fight scene, and sad limping toward the end. But due to that porn interlude, the movie had lost the grasp on its audience the first part had established.
Also, I skimmed through the book earlier today in the bookstore - it's a terrible adaptation. Most of the hole I found in the movie plot are important bits in the graphic novel, and the end/climax is totally different. No high-brow discussion on art or the female orgasm, no first try with a man, and the protagonist's name is different. I think the director really missed the point.
So, did it deserve the Palme d'Or in Cannes? I don,t know - I didn't see the other movies in competition. And technically it is really well amde, and the actresses are very, very good. But it's overlong, tone deaf, and missed to what the source tried to say. I don't recommend it.
PS: I saw the original 3-hours cut with all the graphgic bits in it. I doubt this is the version American Niners will be able to see if the movie makes it to your shore - I would not be surprised if they cut all the sex stuff just to get a R. But honestly, I think that might be a good thing in this case.
I will now take comments/questions.
*Though I wanna make it clear I take umbrage to the use of the term heteronormative to refer to all heterosexuals - that's like using the term "segregationists" to refer to all whites.