When 2008's "Forgetting Sarah Marshall" concluded with the staging of a "Dracula" musical featuring puppets, its inspiration was not difficult to figure out. If anyone could pen a screenplay worthy of resurrecting the Muppets, it was that picture's director, Nicholas Stoller, and its writer-actor, Jason Segel. A lifelong fan of Kermit the Frog, Miss Piggy, Fozzie Bear, and the whole gang, Segel was saddened to see their stars had significantly fallen (their last feature was 1999's stale "Muppets from Space") and a whole new generation of children who might not even be familiar with the late Jim Henson's beloved characters. Three years later, cue "The Muppets," a sequel-cum-meta-reinvention certain to put the brand back in the spotlight. The feature debut of director James Bobin (HBO's "The Flight of the Conchords"), the film is a heart-on-its-sleeve charmer that, nonetheless, can't quite match the loopy energy and genuine fun of the opening ten minutes. Eager to please but too problematic to overlook what's lacking, "The Muppets" strives to be better than it is—the rare movie that is completely worthwhile and disappointing all at once.

Human Gary (Jason Segel) and puppet Walter (voiced by Peter Linz) have grown up as brothers and best friends in Smalltown, USA, sharing a room with matching twin beds into adulthood. Walter, who always felt too short and out of place, has clang to his love of all things Muppets. When Gary and girlfriend of ten years, school teacher Mary (Amy Adams), plan a trip to Hollywood for their anniversary, Walter is invited to tag along in hopes of meeting one of his idols. Their visit to the destitute, all but abandoned Muppet Studios Tour (costing fifty cents per person) reveals just how far the great have fallen. When Walter overhears the nefarious plans that oil tycoon Tex Richman (Chris Cooper) has for the studio lot, it becomes his personal mission to save the day. With Gary and Mary by his side, Walter sets out to find the Muppets, who have disassembled across the globe, and bring them back together for a telethon. If they can raise $10-million, there might yet be hope in overtoppling Tex and reclaiming the Muppets' former glory.

Perhaps the main trouble is that "The Muppets" has been positioned by Walt Disney Pictures as a game-changer in the annals of the series when, really, it's just a solid, lightweight entry, far from the best or worst. For the creators of some pretty heavy-duty R-rated comedies, Stoller's and Segel's dip in the kiddie pool is innocuous and inoffensive, frequently self-referential (when it appears as if the narrative has hit a dead end early on, Mary remarks, "This is going to be a very short movie"), but not nearly as acerbic or edgy as expected. Things never get better than during the show-stopping musical number right at the start, a catchy little ditty called "Life's a Happy Song" that invites the entire town to get in on the singing, dancing charade. For Kermit, who lives by himself in a gated old mansion when Walter, Gary and Mary come knocking, his solo ballad entitled "Pictures in My Head" where he nostalgically remembers his estranged friends is simple and lovely. Another song, "Me Party," in which Mary tries to embrace her singularity after Gary sends her off to sight-see by herself, is deliciously funny and gamely performed by Amy Adams (2010's "The Fighter"). When the too-sparse musical interludes arrive, "The Muppets" is adorable and lively. In between, it's a much safer, by-the-numbers enterprise.

Jason Segel (2011's "Bad Teacher") puts on a contagious smiling face as Gary, certain to be having the time of his life interacting with the Muppets in a major feature film. What he hasn't done is written himself a very good part. Gary is a grown man who has no job that is ever mentioned, and he kind of creepily still shares a bedroom with brother Walter. Despite having aged, Segel plays the character as a stunted pre-adolescent. As Mary, the eclectic Amy Adams is radiant—when is she not?—and that's about all that is asked of her. She mostly just tags along, stands next to Gary, and grins sweetly, not even given a chance to interact much or form relationships with any of the Muppets. The screenwriter half of Segel really ought to have strengthened Adams' role and not made her quite so wishy-washy. As a couple, the two human leads are charismatic and about as complex as a five-piece Fisher Price jigsaw puzzle. Chris Cooper (2010's "The Town") goes radically against-type as the joke-slinging heavy Tex Richman, performing a goofy, self-deprecating rap without embarrassing himself and urging his minions to egg him on by instructing over and over, "Maniacal laugh, maniacal laugh!" Rashida Jones (2010's "The Social Network") is a hoot as the no-nonsense network executive who agrees to air the telethon under the condition that they find a celebrity host. "I will rerun 'Benson' if I have to!" she threatens.

"The Muppets" is less irreverent than it should be and, during the home stretch, not as spirited and momentous as one hopes. The climactic telethon, which should pull out all the stops to entertain, is strangely slow and undercooked, all but tossing Gary and Mary to the wayside and only showing inspiration in the clucking Cee Lo Green cover of "Forget You" by Camilla and the Chickens. The celebrity host they find, which a portion of the narrative hinges upon, is a botch job, the person in question wrongfully introduced in an earlier scene and not nearly "major" enough to deliver upon the intended punchline. With the possible exception of Kermit and Miss Piggy—the latter found working as the editor-in-chief of French Vogue—the Muppets are welcome faces rarely given a chance to stand out from the literal crowd. Letting them loose upon Los Angeles rather than mostly cooping them up on sound stages might have helped to bring out their individual personalities and broaden the story's creative potential. The more one thinks about "The Muppets," the easier it is to pick it apart ("Cars 2" product placement is egregiously tossed into one shot for shameless reasons). It is impossible to write the film off, though, when it's otherwise so big-hearted and innocent. If Jason Segel hasn't exactly broken the ground he wanted to, he at least has made the Muppets relevant and topical again. In an age of faster, flashier, soulless, child-targeted corporate enterprises, reacquainting audiences to the charms of hand puppets is a victory in and of itself.