That was uncomfortable. I can't pretend it's fun, but you can see why it's regarded as one of the greats of American cinema.
It's the story of one of the biggest stars of the silent movie era. Unfortunately this is 1950 and she lives like a recluse, not having worked for decades. She has a butler, more money than she can spend and a dangerously slender grip on reality. That's one of the two leads (Gloria Swanson). The other (William Holden) is a screenwriter on the skids, who used to do respected work in the past but is now churning out shallow hackwork and not even managing to sell that.
It's giving Hollywood a vicious kicking. There had been movie business movies before, but none before had gone to such bloodthirsty lengths to bite the hand that fed them. After seeing it, Louis B. Mayer screamed at Billy Wilder that he should be tarred, feathered and horse-whipped for what he'd done to the business's reputation. This Hollywood is a Darwinian "sink or swim" world, at the heart of which the old silent film stars are still lurking unseen and unalive, like vampires (Swanson) or zombies (the "waxworks"). They avoid the sun. Sometimes they're stark raving mad.
It feels sharp and observed. It's full of real places and people, commented on in acidic Wilder one-liners. Paramount let Wilder put them directly in the film, instead of insisting that he create a fictional studio. (Apparently they didn't even have to be talked into it. They loved what he was doing. Wilder's rushes every day were the hottest show on the Paramount lot.) Furthermore half the cast are playing themselves. Buster Keaton's the guy who passes at the bridge game, for instance. Cecil B. DeMille is first name-dropped as the biggest director in Hollywood, illustrating how unrealistic Swanson's plans are... and then he shows up in person, played by the man himself and getting a healthy chunk of screen time. Wilder doesn't try to protect him. That'll be because DeMille had been an actor on Broadway before becoming a silent movie director.
That's the overt documentary stuff. The "art echoing life" echoes are yet another layer.
Firstly, Gloria Swanson had the same background as her character. She'd been a huge silent-era star, although she hadn't dropped out of the spotlight in the same way and furthermore wasn't insane. Her performance here is fascinating. It's a silent-era performance, but you don't notice because she's also bloody good at the dialogue and making it feel right even opposite the understated, naturalistic Holden. Look at how she uses her face and hands. Just turn down the volume and watch. She twists her hands into claws and holds unnatural-looking poses you'd expect to see in Nosferatu or something... and it's brilliant. She's playing a great actress, albeit one who's out of time, and she achieves it. Her Chaplin impersonation is grotesque and hard to watch, obviously, but it's also good! When she delivers that famous dialogue, she shows us why it's true. "I am big. It's the pictures that got small."
William Holden was an actor, not a writer, but otherwise he fits his role too. In 1950 his career had been on a bit of a downwards drift, but after this he went on to be a big name and an Oscar-winning movie star.
The oddest one is Erich von Stroheim (the butler), who really had been an important silent-era director before killing that career with a refusal to compromise with the studios and show discipline over his films' content and budget. The last straw was probably Queen Kelly (1929), ironically starring Swanson, and Wilder borrowed a clip of it for this film on Stroheim's suggestion.
Anyway, Sunset Boulevard. I can't pretend I enjoyed this film on first viewing, although you'd have to be dead for its conclusion not to blow you away. Holden keeps making the ugly choices, going back to the delicate horror of his life with Swanson. You know how that's going to end, from the opening scene. Wilder's trying to appall you. What's more, it's even worse than it might look to a modern audience, since this is a Production Code movie and so the only way Wilder can imply that Holden is offering his sexual services is to have him embracing Swanson in her bed at the end of Act Two and then to be casually naked and wet in front of her in the next scene. That's "naked" by 1950 standards, anyway. He's wearing swimming trunks.
Nancy Olson's character is adorable, of course, if not as innocent as she looks. We're being shown something sweet, to contrast with everything that's rotten.
There's lots of narration, by Holden. In principle I'm not a big fan of narration, but it adds to those horror undertones to have the film narrated by a dead man, commenting acidly on himself. Wilder originally shot an even more eccentrically horror-movie opening, with corpses chatting in a morgue, but test audiences hated it and so Wilder shot something else instead.
This is not a film about healthy people. Swanson is all kinds of sick and megalomaniac, but Holden's not in a great place either. It's about his humiliation and prostitution, both literally (with Swanson) and less obviously with his writing ambitions. ("Who wants 'true'? Who wants 'moving'?") His big release would be to reject Hollywood entirely and return to Ohio, while I think he only relaxes with Swanson in one scene throughout the film. ("I'm not going to wear earrings, I can tell you that.") Don't expect a barrel of laughs, despite Wilder's dark wit, but it's a poison dagger in the back and it ends with one of the most famous scenes in all cinema.
"Writing words, words, more words! Well, you'll make a rope of words and strangle this business! With a microphone there to catch the last gurgles, and Technicolor to photograph the red, swollen tongues!"