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George Miller’s 2006 penguin-based animated film “Happy Feet” became a surprise smash, and even went on to win an Oscar. It’s safe to predict, though, that while this sequel may repeat its predecessor’s boxoffice success, it won’t be showered with awards. The reaction it evoked most often from this viewer wasn’t joy or pleasure but incredulity, as in: “What were they thinking?”

Director-writer George Miller (who’s certainly strayed far from his “Mad Max” beginnings) and his collaborators have certainly tried to stick with the formula that brought them such success the first time around. “Happy Feet Two” is part Las Vegas stage spectacle and part sentimental “be-true-to-yourself” and “cherish your family” tale. It begins with a massive song-and-dance routine led by Mumble (voiced again by Elijah Wood) and his wife Gloria (Alecia Moore, aka Pink, stepping in for the late Brittany Murphy). But it soon segues into a “Father Knows Best”-style family dramedy when the couple’s youngest chick, Eric (Ava Acres) goes wandering off by himself after failing to catch the dancing vibe. Papa goes off to find him and while they’re away, a collapse of the ice cover traps the whole penguin tribe in a gully, and Mumbles, Eric and a mass of critters from other locales (including a herd of elephant seals recruited for the purpose) create a slope for them to escape by—you guessed it—flipper-dancing in unison.

This is a pretty threadbare scenario, so Miller and his cohorts dress it up with secondary plot threads. Some involve old characters like Robin Williams’ Ramon, who’s desperately searching for a mate while delivering second-rate rants that make him sound like Aladdin’s genie with an accent. (Diversity is important to the movie, even when it makes no species sense.) Others have to do with new ones—Anthony LaPaglia’s elephant seal leader (whose grumpiness, especially at the close, darkens the movie’s tone in a curious fashion) and Hank Azaria’s flying puffin Sven, who’s looking for a home and persuades some of the others they can soar, too, if they only want it badly enough. (They can’t, of course, so the message in this case is oddly short-circuited.)

Then there’s a parallel storyline about two krill (Will, voiced by Brad Pitt, and Bill, by Matt Damon) who detach themselves from their swarm and go searching for adventure because Will’s tired of being at the bottom of the food chain. These are the equivalents of Scrat from the “Ice Age” series, but they’re not nearly as amusing. The characters are beautifully rendered from a visual standpoint (indeed all the animation looks great despite the application of the obligatory but unnecessary 3D), but the sequences devoted to them are verbally nondescript. And since they decide in the end to return to the swarm, their plot thread—along with the penguins’—ultimately sends a message about the value of conformity that’s rather at war with the one about being yourself. (Of course, one can wave away the problem by simply saying it’s all about family and leave it at that.)

“Happy Feet Two” looks marvelous, dahling, as Billy Crystal used to say, but it never rises above the status of mediocre sequel to an original that was overpraised anyway. The musical numbers are surprisingly bland—the songs, mostly newly composed, are no great shakes. And by the time Eric delivers his final big number to the strains of a Puccini aria outfitted with dreadful English lyrics, you might well think that Miller has lost not only his imagination but his mind as well—it’s jaw-droppingly awful. But still the musical numbers are superior to most of the dialogue scenes (except for those involving LaPaglia, whose delivery makes even the worst lines amusing).

And then there are the penguins themselves. Mumbles and Gloria are a colorless pair in every respect, and their kiddies are no better. They and most of their other “tribe” members—save for the rabid Ramon and outsider Sven—have nowhere near the personality of the waddlers in “March of the Penguins,” let alone the ones in “Madagascar” (or Burgess Meredith in the old “Batman” TV show, who outstripped Danny DeVito’s turn in “Batman Returns” by a mile).

The pattern of family audiences heading in droves to sequels is one of the more inexplicable habits of today’s moviegoing public—it makes them as thoroughly conformist as the penguins in this movie. (How else can you explain the continued success of the wretched “Pirates of the Caribbean” movies, except by a sort of cultural brainwashing?) So it’s virtually assured that, like its predecessor, this will be a holiday smash. But what we have here is a case of very flat “Feet.”