Steven Spielberg, Melissa Mathison, Mark Rylance, cinematographer Janusz Kaminski, composer John Williams, newcomer Ruby Barnhill and an army of visual effects technicians clearly worked overtime to invest their adaptation of Roald Dahl’s 1982 novel with magic, but apart from a few sequences the picture doesn’t take flight. “The BFG” fares better than Spielberg’s earlier foray into explicitly children’s territory, “The Adventures of Tintin,” but the sense of wonder that marked “E.T. The Extraterrestrial” eludes it.

The human protagonist in this case is precocious orphan girl Sophie (Barnhill, agreeably wide-eyed) whose habit of staying awake at night to read leads her to see the giant called Runt (Rylance) walking around the city. To prevent her from revealing his existence, he abducts her and takes her to his cave home in Giantland. Though a towering figure as far as Sophie is concerned, and with huge ears that allow him to hear every sound in the world, Runt is considerably smaller than his fellows, who bully him mercilessly. He’s also a vegetarian, while the others regularly go off into the human world to seize children to serve as their repasts. And thanks to an earlier guest, a human boy, Runt is more articulate than the other giants, though his language is littered with malapropisms and floridly goofy terminology that is sometimes in need of translation.

Naturally Runt and his sort-of prisoner bond, and he protects her from his hungry neighbors. He also introduces her to his job catching dream-matter—shimmering clusters of colored light called “phizzwizards”—which he keeps in bottles and then pushes in varied combinations into a huge trumpet, with which he then literally blows the product into the heads of sleeping humans. And one of those he will cause to have a particular dream, at Sophie’s instigation, is none other than the Queen of England (Penelope Wilton, suitably regal but also amiable). The vision is designed to show the monarch that the recent disappearance of English children is the work of the carnivorous giants and that she should, with Runt’s assistance, take measures to remove them to a place where they will never be able to endanger youngsters again.

There are moments in “The BFG” that achieve a modicum of enchantment. The sequence in which Runt and Sophie pass through a glistening pool to reach the upside-down region where the proto-dreams dart about as Runt tries to catch them with a net, like a lepidopterist collecting butterflies, is charming, and the images in the kindly giant’s workshop, where those he’s nabbed are kept in bottles that glow with their radiance, are lovely. The sight of Runt skulking about the London streets also has a creepy elegance. Production designer Rick Carter and the visual effects certainly earned their paychecks, and cinematographer Kaminski gives it all a luscious sheen.

The grand welcome that Runt and Sophie receive at the royal palace, courtesy of not only the Queen but of her sweet secretary Mary (Rebecca Hall) and oh-so-proper butler Tibbs (Rafe Spall), takes the picture into farcical Monty Python territory, and that works as well, due not merely to the serenely nonplussed attitude of the assembled bigwigs and the oversized table and chair constructed for the giant, but the introduction of Runt’s favorite beverage, frobscottle, which induces a round of whizpopping, or happy flatulence in the form of green mist. This sequence is veddy British, but then so is Runt’s loony patois, which is amusing, especially in the moody way Rylance delivers it, though does go on.

Otherwise, however, the movie, while pleasant enough, is rather a lumbering affair. That’s partially due to Runt’s deliberate gait, but also to the sedate pacing that Spielberg and editor Michael Kahn prefer; this is by no means an energetic movie. Williams’ soupy score, ladled on with a trowel, also bogs things down. The most serious defect, however, has to do with the other giants, with names like Fleshlumpeater, Bonecruncher, Butcherboy, Childchewer and Maidmasher. Of the bunch only the first two, voiced by Jemaine Clement and Bill Hader, are consequential, with Fleshlumpeater, who’s equipped with a particularly sensitive nose, proving the most intrusive and bullying. While parents will probably appreciate that the movie doesn’t show the creatures actually feasting on the children they snatch, the mere implication that they do might unnerve some smaller viewers. More important, though, is the fact that the giants aren’t given interesting personalities; they’re just a bunch of drooling, bumptious goons, and it’s difficult even with a vivid imagination to accept that they could invade the human world and carry off anybody without being seen. After all, Ruby catches Runt on his peregrinations.

Nonetheless “The BFG” is likable, though not magical, and a decent alternative to more antic, frenzied children’s fare.