“Thor: Ragnarok” is about half of a pretty great movie. Whenever Chris Hemsworth is flexing his comedy chops, or Benedict Cumberbatch’s Doctor Strange is arching a punctilious eyebrow, or Jeff Goldblum, with blue fingernails and sparkly gold-lame robe, is looming about as an evil whackjob from Planet Disco — whenever these people are onscreen doing these things, the picture is a blast. (Oh, and Valkyrie, too — we’ll get to her in a moment.)

But whenever these characters are (SET ITAL) not (END ITAL) in full effect, we’re left with little to contemplate beyond the exhausted cliches of the Marvel Universe — which is to say, chasings and racings and blowings-up beyond number. (There’s a battle scene with Thor and Hulk that goes on so long, you’d think even the gods of boredom might be moved to call time.) I hope New Zealand director Taika Waititi, a Marvel newbie, had fun deploying these expensive effects (the movie’s budget is reported to be in the $180 million range), but really, it’s his visual wit and respect for the rhythms of comic badinage that the movie could use more of. Maybe next time.

The picture opens with some good-natured genre nonsense. We see Thor in chains, with a flaming hell-beast called Surtur towering above him. “I know what you’re thinkin’,” Thor says, launching into a series of wisecracks that showcase Hemsworth’s matey way with a good line. But once Thor escapes his classically dire situation — and it’s the work of moments, as you might imagine — the musty plot clanks to life. Thor needs to find his dad, Odin (Anthony Hopkins), but discovers that he’s no longer extant on their homeworld of Asgard. (Although Matt Damon is — don’t ask.) Thor makes his way to Greenwich Village to have a beer with Doctor Strange, who tells him to try Norway. This he does, along with his trickster brother Loki (Tom Hiddleston), who’s also back on the scene. They find Odin, who warns them about their long-lost sister Hela (Cate Blanchett), who went bad multi-millenniums ago and is now plotting to institute a global fashion trend for big black-metal antlers and to trigger Ragnarok, the destruction of … well, pretty much everything. If she makes it to Asgard, everybody’s doomed. Can she be stopped? (Kidding — not a question.)

Now the Valkyrie part. Thor comes under the control of this booze-swilling battle chick (played with exemplary sass by Tessa Thompson), and is soon transported by her to some fringe planet run by the batty Grandmaster (Goldblum). Next Thor finds himself in a gladiator stadium facing off against … good grief, it’s Hulk (Mark Ruffalo)! He’s been enslaved here ever since “Avengers: Age of Ultron” ended, two years ago. Thor brings his old partner up to date on a number of fronts (including the news that some people have always secretly referred to him as “the stupid Avenger”), and then, with Valkyrie fully on their side and ready to rumble, they’re off to Asgard to save the world.

Director Waititi’s comedy skill set (he worked with Jemaine Clement on “Flight of the Conchords” and the urban-vampire flick “What We Do in the Shadows”) is the only thing that makes all this shopworn superhero commotion tolerable. He also personally inhabits the role of a new mo-cap character called Korg — your average buncha-boulders fantasy individual, but pretty droll in the riffing department. Chris Hemsworth is enormously appealing, as always (who wouldn’t want to share an eternally self-refilling glass of beer with him?); and Cate Blanchett demonstrates that she can go full-ham with the best of them. As for Tessa Thompson, her Valkyrie is already worthy of a spinoff. Hope she doesn’t have to wait in line behind Scarlett Johansson to get it.

‘Lady Bird’

Saoirse Ronan gives a sensational star performance in “Lady Bird,” a new comedy written and directed by indie eminence Greta Gerwig. The movie is set in 2002, with Ronan playing Christine McPherson, a prickly senior at a Catholic high school in godforsaken Sacramento (“the Midwest of California,” she grumbles). Christine calls herself Lady Bird, insisting that it’s her given name (“Given to me by me”), and there’s not much more to say about that. People tend to humor her.

As the movie begins, Lady Bird is nervously awaiting replies to the application letters she sent out to three fancy East Coast colleges. Her mother (Laurie Metcalf), whose mission in life is to drive her daughter completely mad, wishes she’d consider some non-fancy schools nearer by, especially now that her dad (Tracy Letts) has lost his job.

Meanwhile, Lady Bird has met a boy, a theater nerd named Danny (Lucas Hedges). They’ve recently passed the first-kiss frontier, but who knows if that’ll lead anywhere. Especially now that she’s also pinged the radar of a smoldery hipster named Kyle (Timothee Chalamet), who plays guitar and comes from money. Not that he has any interest in money — he wishes we could all live by barter — but he comes from it. As do his well-off friends, all of whom are very unlike Lady Bird and her ever-present best pal, the sweet, plus-size Julie (Beanie Feldstein). It’s agreeably complicated. And prom’s coming up, too.

Gerwig’s script is a dazzling piece of work, not least because she’s a Sacramento native who knows whereof she writes. (“Anyone who talks about California hedonism has never spent a Christmas in Sacramento,” she has Lady Bird say.) The film is basically a coming-of-age story, but it keeps surprising you. We see Lady Bird and her mom in a weekend ritual, making the rounds of high-end open-house real-estate showings, where they fantasize about what it would be like to live a plusher life. A coach with the school’s sports department subs for an absent theater instructor and runs the class like a gung-ho locker-room strategy session. In a moment of glowing eloquence, the school’s head nun (Lois Smith) tells Lady Bird that the secret of love might not be a lot more than just paying attention. Most memorably, in a movie that’s memorable in just about every regard, there’s a compact sex scene that illuminates a whole interior world of desire and values.

The heart of the movie — the real love story at its center — is the relationship between Lady Bird and her frazzled mother. Ronen and Metcalf operate at the top of their artistry in every scene they share, and we see that their characters do have a bond. (At one point we watch them tooling along in the family car listening to an audiobook of “The Grapes of Wrath” — talk about California illusions.) But their connection is subject to sudden squalls of incomprehension. In a department-store fitting room, failing to elicit an encouraging parental word about a prom dress, Lady Bird asks, “Do you like me?”

“Of course,” Mom says, “I love you.”

“But do you like me?”

Yes, she does, even if that message doesn’t always carry through their crossed emotional wires. “Your mom’s hard on you,” Danny says, trying to commiserate. “Yeah, well, she loves me a lot,” Lady Bird says.