Glee: The 3D Concert Movie opens with footage of concertgoers naming their favourite characters from the hit TV show. Some plump for Rachel "because she's just like Barbra Streisand" (though the actress Lea Michele, interviewed backstage, appears genuinely to believe she is Rachel Berry). Others go for Puck "because he's so sassy, and so into himself". A fair few side with the talismanic Kurt. No-one mentions the divine Miss Tina Cohen-Chang, which would appear a grave lapse of taste on the part of the general public; also unmentioned is just how strange it is to be watching a concert tour derived from a television series, or - weirder still - a 3D movie based on a concert tour derived from a television series.
This perhaps gives some idea of how American television has come to raise its game, as well as its voice, over the past two decades (no-one ever thought of a Who's the Boss? stadium tour, or a 3D Tony Danza), not to mention of the concomitant devaluing of the cinema as a stand-alone experience, free from synergies or 3D specs. You couldn't really imagine a Glee movie existing even after the runaway global success of the show's tonally awkward first season, which hadn't worked out whether to love its characters, or pour another Slushee over their heads. Only with the centralising of the newly-uncloseted Kurt's travails in Season Two did Glee, too, come out, emerging from behind the residual snarkiness of creator Ryan Murphy's previous Nip/Tuck to state, yes, it adored these characters, and everything that made them idiosyncratic, special, fabulous - what made them all stars both within and without the musical numbers that provided the series' USP.
What the film makes clear is that these performers are no mere poseurs or wannabes, but gifted singers and dancers (yes, even Finn), capable of making what are presumably torturous hours of rehearsal and choreography look like immense, infectious fun. It remains a source of wonder - and no doubt inspiration to some - that Kevin McHale gets Artie's wheelchair to function as every bit an extension of his body as Astaire's top hat and cane; Heather Morris, a dancer-choreographer before taking up her role as the series' resident airhead Brittney S. Pierce, gets more self-awareness into her rendition of "I'm A Slave 4 U" than the real Britney has into her last two albums.
Kevin Tancharoen's film is essentially a Greatest Hits package - building from "Don't Stop Believin'" to "A Loser Like Me" - mercifully stripped of the Autotuned vocals that make the show's musical achievements sound unnecessarily synthetic. At least one of my theories about the show gets confirmed in passing: that the best vocal performances - cf. Michele's storm through "Don't Rain on My Parade", Amber Riley's Mercedes doing "Ain't No Way", both reprised here - form some of the least interesting stretches, since they don't quite have the sense of frenzied youth letting rip that mark the uppermost pop artefacts of our time. All Riley's quavering fades into indifference when merged with the intro to Rick Springfield's "Jessie's Girl", which probably isn't even Rick Springfield's idea of a great song, but has an upfront energy this kind of experience thrives upon.
Still, the show operates under an insistently egalitarian banner, and everyone gets their own moment in the spotlight. That this is one for the fans can be deduced from the scene-changers: interviews with real-life Gleeks (forcibly outed gay teenagers, cheerleaders of less than average stature, an adorable pre-teen of Asian extract who knows every word the Dalton County Warblers have ever sung, and will make couples of any orientation want to ADOPT) who both represent the assumed demographic and serve as factual justification for the series' more outré plotlines. As directed by A Small Act's Jennifer Arnold, these inserts come in just north of MTV reality shows, handled as they are with the dorky sincerity that has become the Glee stock-in-trade. Elsewhere, the 3D proves pointless - we were already close to these characters - and haters may well be struck by the disposability of it all, not to mention the weird streak of conservatism that sees kids being whipped up into a frenzy by a crop of prep-school pupils doing acapella versions of old Wings songs.
Yet with the exception of the Black Eyed Peas - Satan's opening act - there's no reason why pop music can't be anything you like, and Glee's disposability, its impermanence, is precisely (and poignantly) the point. Within the show's three-minute wonders, and only within the show's three-minute wonders, anything is possible: you can be straight or gay, and either way receive nothing but applause; folk in wheelchairs can do "The Safety Dance" (and, in this reading, make of it a funny, uplifting old-school showbiz set-piece); anyone above a size-14 can pour their heart out, make themselves heard, and become as much an object of desire as any sylph-like cheerleader; and "River Deep, Mountain High" can finally be reclaimed as the Billboard chart-topper it always should have been. In the Glee universe, sparkly and utopian as it is, we can all be stars, and not even the intervention of Rupert Murdoch's NewsCorp minions - who recently negotiated to remove the series to the realms of pay-per-view - can take that away from us entirely. An effervescent expression of joy through song, the movie stands as one of the happiest experiences this particular grouch has had in a cinema all year.
Glee: The 3D Concert Movie is in cinemas nationwide. An edited version of this review will run in this weekend's Sunday Telegraph.