Anyway, if you share the opinion of my philistine friend, you'll definitely want to avoid Irreversible, which has a happy ending only by virtue of the fact that the film moves backwards in time.
It starts, though, at the end, with what is by far the most realistic and gruesome scene of someone being beaten to death with a fire extinguisher that I've ever seen--much, much more gruesome than the fire-extinguisher-beating scene in Harry Potter's First Erection and way more gruesome than that scene where Jar Jar is bludgeoned to death in Star Wars Episode 7: Jar Jar is Bludgeoned to Death.
I'm not even sure how director Gaspar Noé pulled this scene off, because each sequence in Irreversible is shot without obvious cuts, but somehow he managed to replace a real human actor with an incredibly life-like mannequin. Either that, or he paid someone to have his face smashed in until he was dead.
Assuming that he didn't do that, Irreversible is one of the most technically impressive films I've ever seen. Without a big budget, obvious special effects, or even a tripod, Noé pulls off an amazing feat. Each sequence in Irreversible is a single take (there are a few cases where he steals a page from Hitchcock's Rope by panning to a monochrome area and inserting an invisible cut there), which demands perfection in the movements of the actors and cameraperson.
The camera is particularly mobile, and in the opening scenes, it's almost too mobile, swinging about wildly in a way that makes the film hard to look at. It slowly settles down over the course of the following four or five scenes, until it winds up sitting perfectly still for what is probably the most uncomfortable sequence you're likely to see.
(The following contains a "spoiler," i.e. I give away some of the plot of the film. If you don't want to read the spoiler, stop now. Then again, if you're the kind of geek who worries about spoilers, you probably don't want to see Irreversible anyway.)
In a nine-minute-long segment that has gained the movie much of its notoriety, a woman is brutally raped while the camera lies motionless on the floor, watching from a single angle that emphasizes the victim's face. This scene is horrifying, but cinematically ingenious. Knowing that in most films rape is eroticized, Noé follows suit, using red lighting, flattering shadows, and a victim who is beautiful and dressed in an almost surreally sexual outfit.
Then he lets the camera sit on the scene until it becomes nauseating. While he eroticizes the basic elements, he exposes the audience to the violence for so long, and in such an uncomfortable manner, that there's no way anyone could find this scene titillating. At least I hope no one could, and if you do find it arousing, please don't talk to me at parties.
Past the rape sequence, the earlier parts of the film, i.e. the parts that the audience sees later, but which occur before, are increasingly sweet. In fact, the film has a sort of standard structure, in that it starts with things at their worst and ends with the happiest moment. Of course, since the happiest moment occurs before everything else, they take on a sad and sinister air.
Everything in the movie is designed to emphasize this. The camera's movements become more controlled as the film goes back in time; the music changes from a nasty throb to a quiet Beethoven piece; the lighting alters so that the essentially two-tone opening sequences morph into full, soft color.
The reverse structure allows Noé some interesting cinematic tricks. For example, he foreshadows scenes that have already happened by having the female lead (Monica Bellucci) discuss first a book whose thesis is that everything that will happen is already set in place, and later a dream where she vaguely foresees her attack.
The leads, Monica Bellucci and Vincent Cassel, are the Brad Pitt and Jennifer Aniston of Europe, and they turn in perfect performances in a very demanding film.
There's really almost nothing wrong with Irreversible, except that it's designed to be unpleasant to watch. Basically, if John Ashcroft were to see this film, his head would spin around and smoke would come out of his ears. Which would probably be a good thing, but it should serve as a warning to sensitive viewers that, in spite of its technical achievement, this may not be the best film to take the whole family to.