[three and a half stars]

Roger Ebert thinks 3D is overrated: “Every single frame of a 3D movie gives you something to look at that is not necessary,” he recently wrote. To a formulaic movie like DreamWorks’ “Monsters Vs. Aliens,” however, 3D was the only thing keeping me awake. And in Laika’s stop-motion treasure “Coraline,” the 3D was absolutely integrated into the “Alice in Wonderland”-like story, enriching the storytelling.

I’m not sure if seeing Pixar’s latest animated achievement “Up” in 3D would help or hinder, though. I saw it in regular ole’ 2D, and it is such a genuinely moving tale, that I have my doubts whether 3D would improve the experience. Village Voice critic Robert Wilonsky saw the 3D version and is pretty firm on the matter: “Do not see ‘Up’ in 3D. It’s inessential to the tale and altogether distracting.”New York magazine’s David Edelstein, on the other hand, says, “By all means, see ‘Up’ in its 3D incarnation: The cliff drops are vertiginous, and the scores of balloons–bunched into the shape of one giant balloon–are as pluckable as grapes.”

Either way, go see “Up.”

Co-directed by Pete Docter (“Monsters, Inc.”) and Bob Peterson (who also wrote the screenplay and voices two of the characters), “Up” uses the oft-explored theme of boyhood imagination to propel a story about coping with loss and learning how to live. Sound depressing? Well, at first, it is. And it’s a testament to the artists at Pixar that they keep delivering one piece of expertly-rendered, artful entertainment each year that doesn’t pander to kids and that families will still adore.

With the CGI world in such rapid evolution, “Up” probably could have been made in live-action form. Thank the stars that it didn’t, because the animators pour tons of personality into every pixel of their character design. Carl Fredricksen (voiced by Ed Asner) is a single-minded 78-year-old curmudgeon with a jaw so square you could measure right angles with it. Paralyzed by the loss of his wife Ellie, he comes out of his house only to assault the construction crews that surround him. (Think Clint Eastwood in “Gran Torino,” only without the overt racism and incessant growling.)

An impossibly round eight-year-old Junior Wilderness Explorer named Russell (voiced by Jordan Nagai) comes to the house, interested in completing his “Assist the Elderly” badge. He looks like a Weeble and his unstoppable boisterousness keeps him always on the verge of falling down.

The city won’t get his house if he has anything to say about it, so Carl uproots the entire thing with a massive bouquet of balloons on a mission for the land he and his wife always meant to visit–Paradise Falls, Venezuela. This moment is pure magic, and it sets up a logic-defying second and third act that consistently surprises even as it adheres to a fairly standard formula.

When boiled down to its essence, “Up” is essentially a buddy comedy about a young kid who teaches an old sourpuss to appreciate the joy he had in his past and live again. Even then, the movie tells this familiar story in such an enchanting way that it’s hard to begrudge it. Docter and Peterson imbue inanimate objects with so much meaning that huge moments of change and climax for the characters can happen without them even saying a word.

In fact, a wordless montage that takes place early in the movie could stand on its own as a short film–it’s an incredibly moving portrait of Carl and Ellie’s entire life together. It accomplishes in about 10 minutes what some movies fail to do with two hours or more.

Just because the narrative follows a well-tread path doesn’t mean that “Up” isn’t overflowing with inventive ideas. Plenty of computer-animated movies these days feature talking animals–so much so that it’s become a minor annoyance and a major crutch. Leave it to Pixar to create a new and creative way for this to happen. Using its clever set-up, Peterson even expands on the joke and wrings plenty of empathy out of it.

I won’t spoil it for you, but let’s just say it is just one example of the advanced level of expertly cultivated imagination that has gone into making “Up” such a joy.