Mira Nair’s new screen adaptation of William Makepeace Thackeray’s social satire and classic novel Vanity Fair arrives in a sumptuous package with Reese Witherspoon at its center as survivor Becky Sharp, Thackeray’s born to the bottom rung anti-heroine groveling at the feet of the British class. It’s a lovely and often entertaining film that oddly, despite the presence of a top-flight cast and gifted director, sometimes fails to connect, mostly keeping us at arm’s length just as Thackeray’s anti-heroine does with those on the periphery of her pursuits. Not that Nair and Witherspoon can be faulted for lack of trying, since Vanity Fair is a first-class movie, loaded with gorgeous visuals, terrific acting by a classy British ensemble and a potent social critique that sometimes stings, sometimes falters.

The orphaned daughter of an artist and chorus girl, penniless Becky Sharp finds her emergence into proper society stunted with little hope for penetration. Funny, likable and abundant with wit, Becky is smart enough to know that surviving, without thriving, just won’t do. Scripted by Julian Fellowes, who won an Oscar for Gosford Park, the film’s many characters and storylines are, for a time, engaging. And the cast, including Eileen Eckhart, Bob Hoskins, Jim Broadbent, Rhys Ifans, Jonathan Rhys-Myers, Romola Garai, James Purefoy and a commanding Gabriel Byrne, are all right on the mark, as Becky moves through each of them in her societal pursuits.

Becky Sharp is a classic anti-heroine—a poor yet full-bodied, lust for life, shrewdly canny social climber well played by a loveable American star. But how much we love Witherspoon just might sack the dark side of Becky that makes her such an original and fascinating invention. Witherspoon is effortless in tunnel vision characters like this, from Alexander Payne’s Election to Matthew Bright’s colorfully vulgar Freeway, but what’s needed here is more drive, more push, more gray morality and more of Becky’s scrappy ethical compromises.

What Witherspoon delivers is some of that, and she’s often quite good here, particularly in some of the film’s later passages and one highly effective moment where a critical decision leads to personal devastation. But I often felt like this Becky was politely vaulting and climbing in spite of herself—and there’s the real issue. Becky, a consummate survivor, should be climbing because of herself—and because it is all she has ever known.

In this version of Vanity Fair, we’re torn between Becky’s warmth and remoteness, and maybe that’s part of her complexity. There’s also a real problem with Becky’s age—the film requires her to cross decades from a teen to her mid-thirties—and to my eye, there’s not much difference, if any, in Witherspoon’s visage.

Nair, the humanist director who has given us such varied, sumptuous and often politically charged films—Salaam Bombay!, Mississippi Masala, Kama Sutra and Monsoon Wedding—has said that Vanity Fair is one of her favorite novels. She certainly embraces the essence of what makes Becky Sharp such a great survivor—her grand style.

Flawed as it is, Vanity Fair is also funny, intelligent and romantic. Nair shrewdly posits her Vanity Fair as a film about energy and determination, deals and sacrifices—and she moves heaven and earth to take the inherently uptight drawing room tea and crumpets feel from the story, opening up the settings and allowing the color palette to be deeply saturated and, at times, as exotic and as seductive as Becky herself.

With a pedigree like this, Vanity Fair should have been a great film. It remains a gorgeous if unaffecting fling.