Five years since its release, "Happy Feet" continues to stand as a rather unorthodox animated family feature—crowd-pleasing, certainly, but also tough and non-pandering, a coming-of-age musical mash-up that dared to journey to some dark places to more effectively express its ecological message. "Happy Feet Two" has loftier aims, too, but lacks the courage of its convictions on the follow-through. Perhaps as a sign that everyone behind the scenes had to struggle to find a viable story since there really wasn't another one to tell, returning writer-director George Miller, accompanied by co-scripters Warren Coleman, Gary Eck and Paul Livingston, lob on bathroom humor that was nowhere to be found in the original—i.e., pee gags, snot bubbles—while overstuffing the flimsy narrative with supporting characters who only truly serve as filler. Markedly long-winded despite being shorter than its predecessor, the film finally results in a lot of standing around trying to figure out what to do next. Only the series' bread and butter—the song-and-dance performances—are able to occasionally buoy the flagging energy.

In the Antarctic kingdom of Emperor penguins, Mumble (voiced by Elijah Wood) can't really carry a tune like the rest of his tribe, but he more than makes up for it with his natural, out-of-this-world dancing skills. Now that he and Gloria (Alecia "Pink" Moore, replacing the late Brittany Murphy) have a young son of their own, Erik (Ava Acres), Mumble sees a lot of himself in his chick. With two left feet, Erik feels like an outcast without a talent to call his own. His running away coincides with the first signs of the melting ice caps, the green grass a foreboding sign that the penguins are at first more intrigued by than concerned about. Things become a great deal more dire when the ice shelf shifts, stranding most of the tribe in a gorge that they cannot get out of. With Gloria stuck down there trying to be a calm voice of comfort for her fellow penguins, Mumble seeks the help of the Adelie penguin tribe led by Lovelace (Robin Williams) and the Mighty Sven (Hank Azaria), a penguin who can somehow fly, to plot a recourse for saving and reuniting with the endangered families.

When the penguins in "Happy Feet Two" are crooning their little hearts out, it's enough to make one temporarily get lost in the toe-tapping music and forget about how inferior the rest of the film is. The opening number, a medley that includes Chaka Khan, Justin Timberlake, and Janet Jackson's "Rhythm Nation," jump-starts things on a high note and is at least diverting for a time as Mumble tries to parent a son who is going through a lot of the same adversities and soul-searching that he once did. The sloshy, melted water on top of the ice as the characters dance around will not be lost upon anyone familiar with this series' environment-friendly modus operandi, and sure enough their frozen tundra is soon showing tell-tale signs of spring that it really shouldn't be. Director George Miller embellishes the reality of global warming to make a point, but then doesn't really deal with the subject, unwilling to see any further into the future than the penguins' immediate predicament. The picture ends with the line, "No worries," sweeping the bigger problem and graver dangers heading these characters' way conveniently under the rug. It's thematically and emotionally dishonest, a slap in the face to younger audiences who could have stood to learn a little something not wrapped in a candy-coated shell.

Returning protagonists Mumble, Gloria, and Latino Adelie penguin Ramon (Robin Williams) are joined this time by Ramon's spicy lady love Carmen (Sofia Vergara); the aforementioned Mighty Sven, who may be hiding the real reason why he can fly; trusty elephant seal Alpha Skua (Anthony LaPaglia); and shrimp-like krills Will (Brad Pitt) and Bill (Matt Damon), who begin to wonder if there might be more to life than just mindless swimming amidst a swarm of their own kind. These latter two creations are given an ongoing subplot where they restlessly try to find a larger purpose in life while spouting off double-entendres and bad puns ("Goodbye, krill world!" one of them says). What is of note is the love story that grows between Bill and Will, complete with a serenading of Rick Astley's "I'm Never Gonna Give You Up" and cursory plans to adopt together. It's surprisingly forward-thinking and sweet in its own way. Other highlights include, well, the other parts where singing is involved. Alecia "Pink" Moore performs the gently poignant "Bridge of Light," the Northern Lights gleaming brilliantly above her in the sky, while O-Zone's "Dragostea din tei" and plenty of Queen ("We Are the Champions," "Under Pressure") also figure in.

When the music stops, "Happy Feet Two" flounders. Erik's discovery of his personal gift includes a lovely little payoff, but the remainder of the film drags on without any forward momentum. It is one thing for live-action actors to appear stranded by a less-than-sound script and directorial vision. It is quite another for your computer-animated characters to end up looking at each other with a loss for what to do and say. This happens for interminable stretches here, director George Miller running out of a story to tell and then prolonging the inevitable so that a feature length can be obtained. What might have worked better at 75 minutes, however, fast becomes listless and even boring at 99. It's neither funny nor made dramatic enough to make an impact. There is an air of desperation in "Happy Feet Two" both unmistakable and understanding. A shadow of its brighter, more meaningful precursor, the picture should be forgotten as time goes by even as the first "Happy Feet" continues to endure.