The DUFF could stand for for Disappointingly Underwhelming Feature Film.

Falling some way short of classic teen movie status, “The DUFF” is still a likeable and passably entertaining high school comedy version of “Pygmalion”: a “She’s All That” for the “iCarly” generation.

When her neighbour mansplains to Bianca that she is, in fact, her friends’ DUFF (Designated Ugly Fat Friend), it sparks off a crisis of confidence that sees her try to shake off her image and change herself into one of the popular crowd in order to win the boy of her dreams. Standing in her way is the petty and spiteful would-be Prom Queen determined to undermine any attempt to change the status quo.

The lightweight and forgettable collection of teen high school movie tropes is held together by a winningly quirky performance from Mae Whitman (who played President Whitmore’s daughter in “Independence Day”, trivia fans). Like a transporter accident fusing of a young Janeane Garofalo and Melissa Joan Hart, Whitman’s Bianca is an appealing blend of feisty snark and innocence as she deals with the various dizzying highs and end-of-the-world tragedies that tend to punctuate teenage life (from what I can dimly remember).

That’s something the film and I have in common, actually – a little bit of a problem remembering exactly what it was like back then. There’s a lack of authenticity to the teen angst thanks to a cast which, it’s abundantly clear, are far closer to their thirties than their senior year of High School and there’s a whiff of desperation to the wannabe-Diablo-Cody-riffing script which wants nothing more than to become endlessly quotable but ends up – unironically – using passé slang like ‘amazeballs’ repeatedly. Lame.

Apparently bearing only a passing resemblance to the book it’s based on, the script does try to tackle some unexplored areas, specifically cyberbullying but finds it hasn’t got much to say on the matter beyond a vague ‘that’s bad, m’kay?’ and ends up tripping over its own feet attempting to be both pro-being yourself and pro-changing to be happy. It all ends happily enough, although those hoping for deliciously ironic justice for the mean girls may be let down by the lack of genuine payback.

While Whitman carries the entire film with charm and charisma, the movie wastes other cast members such as the great Allison Janney, who relegated to the sidelines for much of the picture yet still manages to steal a scene or two. Ken Jeong initially starts out in his usual frenetic kitsch style, like an ADD Yoda, but thankfully tones it down for the rest of the film, bringing some calmness and even a hint of compassionate wisdom to his character. In Robbie Amell (TV’s “The Flash”), though, Hollywood has found itself a new Freddie Prinze Jr: every bit as handsome, chiselled and safely bland as the original. He’s a cookie-cutter leading man, generic enough to be replaced by the crush-du-jour of the movie’s target audience without them missing a beat.

Undemanding, amusing – but nowhere near as comedic as the trailer would lead you to believe – and sweet, this is a lightweight bag of teen movie pick ‘n’ mix which will fade from memory almost as soon as it’s been eaten.