Now that the mosaic has finally been put together, what does it look like?

“The Other Side of the Wind” tells the story of a legendary Hollywood director, Jake Hannaford (John Huston), who is struggling to complete his latest picture. Considering that it took more than 40 years to assemble Orson Welles’ final film into something that resembles finished form, the first question to ask about it is: Does it play like a fully realized movie? The answer (more or less) is yes. The diligent team of archivists and technicians who labored to complete “The Other Side of the Wind,” led by the Oscar-winning editor Bob Murawski (“The Hurt Locker”), have tackled the 100 hours of footage Welles left behind (along with his extensive notes) as if this were a hallowed cinematic archaeological dig. What their work lays bare is an eccentric, rather choppy, but highly watchable movie, and Orson Welles is quite alive in it. You can feel the intensity of his DNA in its sinister atmosphere of garish noir depravity.

So is it a good movie or a bad one? A fascinating jumble or a searingly told story? A work of art or a curio? Let’s say that it’s a little of all those things. “The Other Side of the Wind” has many characters (though a number of them just pop up to gawk into the camera and detonate a line or two). It has a loose but flowing party-into-the-dead-of-night structure, as well as a ripely jaded atmosphere of Hollywood insider dread. It also comes at you in scrappy bedazzling fragments and a variety of film stocks (35mm and 16mm, black-and-white and color), though the movie, which Welles shot in bits and pieces over a period from 1970 to 1976, isn’t a sketchy, one-man-band fever dream just because Welles died before he could complete it. Judging from the evidence, a sketchy, one-man-band fever dream is what “The Other Side of the Wind” would have been even if he’d finished it.

Welles was 55 when he returned from Europe to begin work on this project. He conceived it from the start to be his comeback film, and it’s clearly intended as a magnum opus — Welles’ grand statement on Hollywood, the media, the new youth culture, and the twisty politics of making movies. But the film is still executed in the style of the visionary low-budget I’m-making-a-film-on-the-road-as-fast-as-I-can home movies (“F for Fake,” “Don Quixote”) that Welles directed during the last phase of his career. The DYI aesthetic of those later films was built on a wish that’s also a kind of monomaniacal fantasy. Welles, the genius martyred by the Hollywood system, had turned himself into the ultimate filmmaking outsider, yet the desire that fueled his later movies was this: Without much budget or crew, let alone a studio factory behind him, could he shoot a movie in such a way that the sheer power of his technique — the camera angles, the acid dialogue, the vision — would add up to that magical thing: a true Orson Welles film?

That’s an arresting dream to have, but it’s hard to escape the suspicion that one of the reasons Welles never completed “The Other Side of the Wind” is that on some level he didn’t want to. For him, the alchemy of filmmaking had become more holy than the finished film itself. Never finishing the movie was the self-glorifying, self-destructive Welles’ way of saying that where Hollywood made products, his filmmaking passion transcended the finished product. The purity of the process was all.

In “The Other Side of the Wind,” this meta-indie, live-for-art, I-am-a-camera way of cobbling together a major motion picture produces a tall tale of Hollywood extravagance that, in a funny way, becomes a heady example of the very sickness it’s diagnosing. Hollywood, according to Welles, was the dream factory that didn’t allow you to tell the truth. “The Other Side of the Wind” is an underground dream-gone-nightmare that turns the truth into a fleeting mirage.

At first, we feel like we’re watching the rough schematic of a movie that isn’t quite there. The opening 20 minutes are twitchy and disorienting; the film keeps hurling out characters and lines of dialogue, none of which quite add up to that thing called a scene. It’s as if Welles had never heard of an establishing shot — which could be a stylistic choice, or just one of the consequences of shooting a film on the fly. Yet even here, “The Other Side of the Wind” is never less than a fascinatingly quirky record of its own making. From the start, several performers pop out at you, notably Peter Bogdanovich, who infuses the role of Brooks Otterlake, an unctuous hotshot cinéaste filmmaker who is Hannaford’s protegé, with his own self-promotional oiliness. One of the film’s conceits is that a documentary is being made about Hannaford, and everywhere you look there are people holding cameras, and talking about holding cameras, which becomes Welles’ statement about the budding ’70s media age — but plays now almost like his anticipation of the iPhone era.

“The Other Side of the Wind” doesn’t take hold as an act of storytelling until it reaches the desert ranch house where everyone has gathered for a party to celebrate Jake’s 70th birthday. His cronies, fixers, groupies, and hangers-on are there, and so are a few of his enemies, like a film critic (Susan Strasberg) who keeps tweaking him, and so are Welles’ young director pals, like Paul Mazursky and Henry Jaglom, who sit around and debate the class war. After a while, John Huston, acting with the same leering, knowing rot that made his performance in “Chinatown” so mesmerizing, steps into the dramatic spotlight, and the move begins to hum.

Is Huston playing a Welles self-portrait? Yes and no. Hannaford, who’s as old as motion pictures, is a fixture of Hollywood who goes back to the silent days, and he knows all its dirty secrets, some of which are his. He’s a “man’s man” director, a Hemingway/Hawks figure who towers over a room, and he has a way of growling out Wellesian pensées like “I think it’s relatively easy to make a good movie. Not a great movie — that’s something else,” or “It’s all right to borrow from each other, as long as we don’t borrow from ourselves.”

Hannaford is part of the Hollywood power elite in a way that Welles never was after “Citizen Kane,” but he’s also a relic from a fading era. The studio system on which Hannaford built his legend has crumbled, and a new Hollywood — or maybe the end of Hollywood — is in the air. Like Welles, he’s returning from a period of exile in Europe, though the movie he’s trying to finance to completion couldn’t be less Welles-like. It’s an arty psychedelic youth-movie freak-out called “The Other Side of the Wind,” and we see extensive sections of it — first in a screening room, where Billy Boyle (Norman Foster), Hannaford’s hatchet-faced associate, is trying to sell the film to a potential investor (Geoffrey Lamb), who walks out in the middle of it.

It’s hard to blame him. The movie-within-the-movie is meant to be Welles’ satire of an Antonioni youth flick. It starts off looking like “Zabriskie Point 2,” with John Dale (Bob Random), the blue-eyed Jim Morrison leading man, standing around on barren landscapes opposite the leading lady (known only as The Actress), who is played by Welles’ paramour, the voluptuous Oja Kodar, in a state of ongoing semi-nudity. We see more of the film later on, when Jake screens it at the party, and it turns into a free-floating satanic rock ‘n’ roll acid thriller. But it’s hard to get a fix on just what Welles was intending here. We can giggle at a few of the scenes, but many of them are glumly inert, and if that’s Welles’ statement on the films the New Hollywood was starting to produce, it looks trendy and (in hindsight) behind the curve.

Far more arresting is the party itself, which plays like a boozy orgy of poison-dart epigrams. The dialogue in “The Other Side of the Wind” has a malignant cold snap. “Jake is just making it up as he goes along.” “The man is infested with disciples.” “Hemingway — that left hook of his was overrated.” “Mr. Hannaford enjoys pretending to be ignorant.” “He’s a man who can take a terrible idea and make it absolutely atrocious.” “Please, if you’re going to fight, invite me.”

If the verbal attack is jaded literary noir, the film’s visual style, a cousin to the rapid-fire technique Welles developed in “F for Fake,” remarkably anticipates the hypnotic language of multi-media doom that Oliver Stone used in “Natural Born Killers,” to the point that you can’t help but wonder if Stone got a good look at the 40-minute section of this movie that Welles assembled. It’s not just that the leaps from color to black-and-white keep us off-balance. They invite us to view the characters as reptiles in a cage.

The juicy satisfaction of finally getting to see “The Other Side of the Wind” is that so much of the movie is so Wellesian. The film of his it probably comes closest to in mood is “Touch of Evil” (to me, Welles’ greatest work after “Citizen Kane”), and it even has a kind of Rosebud, which is Hannaford’s hidden homosexuality, expressed in his ambiguous relationship with John Dale (“He was selling vacuum cleaners when Jake discovered him”). The film presents this as more than mere gossip. It’s Welles’s metaphor for the fakery of Hollywood — this macho director who has built himself, and his movies, on the edifice of a lie about who he is. It is also, on a Freudian level, the ultimate excuse for not finishing a movie. (John Dale walked out on “The Other Side of the Wind,” so if Hannaford had come clean about his own nature, maybe he could have completed it.)

But let’s be honest: Evoking “Touch of Evil” and “Citizen Kane” isn’t the same thing as matching their artistic power. “The Other Side of the Wind,” coherent and compelling as it often is, remains an arresting scrapbook of a movie that we no longer have to speculate about. What you’ll still wonder about is the movie it might have been had Welles made it from the start on the grand scale it deserved, so that you didn’t have to feel it’s a dream that, on some level, will forever be locked up in his head.