When Sony and AEG announced in August that they were partnering to release a film chronicling Michael Jackson's final preparations for his ill-fated London tour, cynics expected little more than a ghoulish glimpse into the troubled pop star's last desperate days before his untimely death. But even the hardiest of cynics will find themselves tapping their feet, bobbing their heads and perhaps even clapping their hands at times during This Is It, an exuberant tribute to Jackson's unsurpassed musical legacy. Indeed, the only real revelation that emerges from This Is It is how alert and engaged Jackson appears throughout his rehearsals. Lithe and lucid, he executes every signature dance move with the confidence and precision of an artist half his age, showing no signs of any ill effects from the various painkillers and other medications to which he was allegedly addicted. Director Kenny Ortega wisely keeps the focus on Jackson's music and performances in this film, providing a vivid depiction of the scale and magnitude of the show he and Jackson planned to present during their yearlong run at London's O2 Arena.

The camera keeps a safe distance from the legendary artist, offering only a handful of candid moments as Jackson alters a song arrangement, directs his back-up band or choreographs a dance routine. While a number of dancers, musicians and crew members from the tour were interviewed for the documentary, Jackson was not. At no point in the film are there any references made to Jackson's death. All of the interviews were recorded prior to his passing, and most serve merely as filler between exhilarating performances of ''Wanna Be Startin' Somethin'," "Beat It," "Billie Jean," and a host of other classics from Jackson's platinum repertoire. The only point when the action lags is during the latter third of the film, when Jackson cycles through some of his more recent, lesser hits, and expounds (via voice-over) on his love of nature and concern for the environment.

For all of the youthful vigor Jackson displays throughout This Is It, it's hard at times to ignore the sight of his gaunt, emaciated frame, most notably during a rendition of "The Way You Make Me Feel," in which his female dance partner -- herself rather slender -- practically dwarfs him in size. Watching him work, expending so much energy in the process, one can't help but wonder if the slight, 50-year-old Jackson would have been able to endure an entire year of performances. There are a few scattered moments in the film in which Jackson betrays his eccentricities as an artist, like when he issues indecipherable directions to his politely puzzled music supervisor, laments the harmful affects of a performance of "I Want You Back" on his inner ear, and delivers a rambling soliloquy to his crew at the end of rehearsals. But those only serve to reinforce the impression that, however much of a mess Jackson may have appeared offstage, he was firmly in control of his faculties while on it. Which, ultimately, makes the reality of his tragic personal life all the more heartbreaking.

Hollywood.com rated this film 3 1/2 stars.-Thomas Leupp.