(CNN)The appeal of “Judy” is as simple as its title — watching Renee Zellweger inhabit the role of Judy Garland near the end of her life in boozy, jittery, soaring fashion. There are virtually no surprises in this dutiful biography, which could easily be a sort of gender-switch “A Star is Born,” only with Garland portraying the aging superstar.
Set in 1969 — three decades after she donned the ruby slippers — the movie opens with Garland and her children being ousted from the hotel where they’re residing, forcing the kids to move in with her ex, Sid Luft (Rufus Sewell), and Judy to grudgingly take a gig performing in London, seeking to restore her finances to a place where she can be their live-in mom again.Remember when Judy Garland wore a gingham pinafore in "The Wizard of Oz"?“I’m unreliable, and uninsurable,” she says flatly, when someone suggests that she do another movie.Getting her on stage, however, is no simple task, as Garland’s pill-popping habit lingers, the roots of which are traced to her days as a contract player at MGM, in heartbreaking flashbacks that depict the young Judy (Darci Shaw) being verbally abused and bullied by legendary studio boss Louis B. Mayer (Richard Cordery), circa “The Wizard of Oz.”Filled with need, anger and apprehensions, Judy receives some support from Rosalyn (Jessie Buckley), the Brit assigned to wrangle her, but that’s balanced against the young woman’s mandate to do her job, which is to find a way to ensure that Garland appears every night, regardless of her condition. The remarkable part is that when it all clicks, the entertainer can still dazzle an audience, though with the pharmaceutical complications involved, the process never stops being a crapshoot.Read MoreDirected by Rupert Goold from a script by Tom Edge adapted from the play “End of the Rainbow,” “Judy” occasionally soars in those flashes of Garland entertaining, which Zellweger — who also handles the singing chores — brings to life with abandon.At the same time, the idea of a star held together by booze and pills, thirsting for a final hurrah, is such a well-worn cliché that even the fact-based underpinnings can’t really prevent the movie itself from feeling a trifle humdrum, the showiness of its central performance notwithstanding.Perhaps the best sequence involves a gay couple who frequent Garland’s shows, with whom she shares a tender moment — them wowed by being in their idol’s presence, her just in need of a meal with friendly faces. It’s a little too perfect but invests her with an element of discovery that’s otherwise mostly lacking, especially compared to Garland’s relationship with a shady opportunist (Finn Wittrock) who quickly insinuates himself into her life.Sid Luft, Judy Garland and Joey Luft in ‘Sid & Judy.'”Judy” is well worth seeing, if not necessarily rushing to a theater to experience, thanks to Zellweger’s uncanny ability to replicate Garland’s quirks and still locate the humanity and fragility within her. (“Sid & Judy,” a documentary airing on Showtime in October, also offers a fine companion to the movie, for those interested.)”I’m only Judy Garland for an hour a night,” the former Frances Gumm laments at one point.Somehow, Zellweger manages to be Judy for a full two hours, delivering an over-the-rainbow performance in a movie that otherwise, on balance, is a bit more Kansas than Oz.”Judy” premieres Sept. 27 in the US. It’s rated R.