During my preadolescent and teenage years, I devoured each and every review featured in the annually released editions of "Roger Ebert's Movie Home Companion." To this day, fifteen-plus years later, I can still recite portions of Ebert's stirring critical essays, from his four-star write-up of John Carpenter's "Halloween" to his poetic, thoughtfully composed assessment of a personal favorite, Joyce Chopra's coming-of-age drama "Smooth Talk." Likewise, it was a weekly tradition to record on videocassette the latest "Siskel & Ebert," and it was certainly not out of the ordinary for me to return after the fact to each episode (Ebert's venomous diatribe against 1994's "North" is forever ingrained in my memory). For a young movie buff and aspiring writer living in a pre-Internet world, the 13-year-old me identified with Gene Siskel and Roger Ebert, seeing in their love for the cinema my own adoration for the art form and hunger to learn more about it. If there were living inspirations who helped to inform my path toward film criticism, they were it.

In the remarkable new documentary "Life Itself," a compendium to Ebert's 2012 memoir, director Steve James (1994's "Hoop Dreams") gets to the heart of precisely what its title infers. Acting as a celebration and eulogy of a person who lived fallibly, bravely and—most important—fully, the film flawlessly, heartbreakingly captures the transcendence of one's ever fleeting existence. James began filming five months before Roger's passing with the critic's full support. Left without a jaw following surgeries related to thyroid and salivary gland cancer, he exhibits no vanity in front of James' camera, insisting to the filmmaker that he wanted the picture to, above all else, show reality. Despite so many health setbacks and a disease that stole his ability to speak, eat and drink—a nurse is seen on a few occasions putting a tube directly into his throat to feed him—he never stopped corresponding with readers on his RogerEbert.com blog and writing about movies (his last review, for Terrence Malick's "To the Wonder," was filed just days before he died). Indeed, it seems like it was these things on top of his unwavering love for wife Chaz that kept him going through his darkest of times. They were his life's work, and the impact that said work had on multiple generations of cinephiles is incalculable.

Through home video footage, photographs and sometimes moving, other times funny interviews with the friends, family and acquaintances who knew him best, Roger Ebert is brought back to life for two sweeping, stunning, magical hours. Tracing his early days as a paperboy growing up in 1940s Urbana, Illinois, before jumping into his post-college career and the chance events in 1967 that led to him taking over as the Chicago Sun-Times' resident movie critic, the film is at once in awe of his gifts as a writer and candid about his faults and addictions. A man about town in his twenties who could often be found swapping stories with colleagues at the local bar, he went on to become the unlikely co-screenwriter of Russ Meyer's X-rated 1970 satire "Beyond the Valley of the Dolls" and, later, the host of a local public broadcasting television series called "Sneak Previews." When the show moved to PBS for national distribution in 1978, rival Chicago Tribune critic Gene Siskel joined him on the balcony. Their careers and influential notoriety, as it were, took off, but Ebert would have been fine regardless; he had, after all, already won the Pulitzer Prize for Criticism three years earlier.

In vintage clips, Ebert and Siskel are seen sparring on-air about any number of films (they almost come to blows over "Full Metal Jacket" and "Benji the Hunted") and even more so in mesmerizing outtakes from the tapings of their weekly promo bumpers. Their relationship is described as "radioactive"—it was a point of contention that Roger's screen partner's name came before his when their show was rebranded "Siskel & Ebert"—but the friendship that bloomed from their years together is affectionately recounted by Chaz and Gene's wife Marlene Iglitzen. When Siskel was diagnosed with terminal brain cancer in 1998 and opted to keep the news private until his final days, Ebert is described as being deeply, lingeringly affected by it. These scenes, as well as photos shown of Ebert helping to carry his casket at the funeral, are especially powerful. In contrast to this sadness, Roger's and Chaz's marriage is what great love stories are made of. At a time when Roger had more or less given up on finding his soul mate, trial attorney Chaz walked into his life at, of all things, an AA meeting. Wed in 1992, he gained a family at the age of 50 and a partner who, as he puts it, "saved me from a life of being alone." Seeing them together in more vibrant days and getting a peek into the steadfast beacon of light and support Chaz was for Roger up until the very end provide a certain solace to the bitter truths involving one's fight to live and the inevitability of dying. Everyone should be so lucky to find that special something that these two shared.

As his moment of transition arrives, Roger's spark dims and his electronic Q&A correspondences with documentarian Steve James begin to trickle before stopping altogether (his final text to him: "I can't"). Ebert had said many times that he was not afraid to die, that it was something that everyone eventually must go through, and Chaz's recount of his final moments are crushing, honest and indescribably beautiful. James has not made a film about a perfect man or a martyr or even someone who was always entirely kind ("He was nice," one of his old drinking buddies remembers, "but he wasn't that nice"). Instead, he has created an authentic, impassioned, wholly formed, emotionally sublime tribute to someone who was human in his flaws, who was generous with his time, who lent support to aspiring filmmakers, who took advantage of the gifts inside himself and turned them into art. He may no longer be here, but his impact and legacy will endure. For someone who loved movies as much as he did, Roger Ebert would be pleased to find that "Life Itself" is one of the year's very best.