Disney's latest live-action update of one of its classic animated features is "The Jungle Book." But don't expect just a shiny CG update of the 1967 cartoon that turned Rudyard Kipling's fierce beasts into mostly adorable, toy-ready critters. For one thing, if you've seen the trailers, you know this new version features some impressive-looking animals, speaking with the voices of some impressive stars. For another thing, its director is Jon Favreau, who helped launch the Marvel Cinematic Universe with "Iron Man."

Favreau and Disney clearly wanted to make something more than just a retread of the studio's 1967 cartoon -- or Disney's 1994 live-action version. Judging by the 100% approval rating from critics on Rotten Tomatoes, they've pulled it off. Here are five things you need to know before entering the "Jungle."

1. Think 'Avatar,' Only Earthbound

The James Cameron epic is a movie Favreau has name-checked often in describing the exotic, immersive, 3D forest world he's tried to create here. From its setting to its jungle animals, Favreau's film is almost completely CGI -- except, of course, for Neel Sethi, the 12-year-old New York native who plays wild boy Mowgli.

Favreau and his effects team shot the whole film on stages in downtown Los Angeles, digitally added lush vegetation, and populated it with creatures based on the appearances and movements of real animals -- but given an artistic flourish by digital animators. Imagine the CGI tiger in "Life of Pi," except that he's moving his lips as Idris Elba's (above) menacing voice emerges from his mouth.

2. This Is No Cartoon

The generally-lighthearted 1967 cartoon wasn't especially faithful to the source material. Favreau has said his film delves deeper into the Kipling stories, which means the animals are more savage and the danger to Mowgli is greater. Elba's tiger Shere Khan is reportedly one of the scariest screen villains since -- well, Elba's warlord in "Beasts of No Nation." No wonder some critics are calling the film a kiddie "Revenant."

3. It's Not Just a Guy Thing

Favreau decided that the cartoon, populated almost exclusively by male characters, needed more feminine presences. So Kaa the Python got a sex change; she's voiced by Scarlett Johansson (pictured). Interestingly, in "Jungle Book: Origins," Andy Serkis' upcoming 2017 take on the same public-domain Kipling stories, which will also mix live-action actors and motion-capture animals, Kaa will be female as well, voiced by Cate Blanchett.

Favreau also beefed up the role of Raksha, the wolf mother who adopts Mowgli. She doesn't even speak in the cartoon, but here, she's voiced by no less a luminary than Lupita Nyong'o.

4. The Animals Are Zoologically Correct

Well, except for the whole talking thing. But at least Baloo (Bill Murray) is now more obviously a sloth bear, a mammal native to India, than the generic bear of the cartoon. Alas, there are no orangutans in India, so King Louie (Christopher Walken) is now a Gigantopithecus (pictured), an orangutan-like ape that is now extinct but which did once live in India.

5. Don't Worry, Your Favorite Songs Are Still Here

Darker tone aside, Favreau made sure to keep some of the cartoon's comic-relief moments, as is apparent by the casting of Murray and Walken. (The late Garry Shandling is here, too, as a nervous porcupine.)

Baloo does get to sing "Bare Necessities" and Louie still sings "I Wan'na Be Like You." Richard M. Sherman, who wrote that song's lyrics 50 years ago, has updated the words for the new film. And Kaa still delivers the hypnotic "Trust in Me" -- though, instead of Sterling Holloway's Winnie-the-Pooh bluster, the snake now purrs the words in Johansson's seductive, unsettling rasp.

"Jungle Book" hits theaters Friday.