At one point in Life Itself, Steve James’ documentary based on Roger Ebert’s 2011 memoir of the same name, Ebert’s wife, Chaz, wryly mentions that her husband is “death-obsessed”—an understandable position, given that at this point in filming, Ebert was in the midst of what would turn out to be the last of many, many hospital stays during his 11-year battle with cancer. But there’s an overwhelming sense that Ebert’s fixation on death is simply an extension of his zeal for life in all its complexity, which Life Itself embodies from its title on down. Death is a part of life—one that informs everything we do, on some level or another—and watching Ebert characterize whatever time he has left as “money in the bank,” from what viewers know is his deathbed, is life-affirming and heartbreaking in equal measure.

Those hospital scenes help make what could have been a fairly straightforward profile a remarkable piece of documentary filmmaking, as much a discourse on life and death in general as the story of one specific, extraordinary life. Credit for that certainly goes to James, but also to Ebert, who helps the director orchestrate the movie as it’s filming, via onscreen emails and the computer software that allowed him to speak when his body would no longer let him. When Ebert cheekily orders James to film himself in the hospital-room mirror, or sends the director an email expressing glee that they got some grody footage of his G-tube being suctioned out, it’s clear he considers himself more than just the subject of this film.

Such moments of fourth-wall-breaking are appropriate in the context of Ebert’s life, a good portion of which was spent hobnobbing and collaborating with the filmmakers he wrote about in his official capacity as the Chicago Sun-Times’ film critic, and later, as the co-host of Sneak Previews and At The Movies. (James is among those filmmakers; Ebert, along with Gene Siskel, was a vocal advocate of Hoop Dreams when it came out in 1994.) Ebert wrote about film, yes—prolifically, astutely, and seemingly effortlessly—but he also lived it, and the filmmakers he befriended along the way were cast members in the movie of his life. Many of them are actual cast members in Life Itself as well, including Martin Scorsese (who also executive-produced), Werner Herzog, Errol Morris, Ramin Bahrani, and Ava DuVernay, who all contribute fond remembrances of Ebert as both a critic and person.

But not too fond. Appropriately, Life Itself is reverent while still being critical of its subject, acknowledging his flaws (his alcoholism, his terrible taste in women pre-Chaz, a prurient streak that led, among other things, to his collaboration with Russ Meyer) in the context of his humanity. The film’s overview of Ebert’s rivalry with Siskel in particular is fascinating for the glimpse it provides of both men’s insecurities, as well as their biting wit; a blooper reel of At The Movies where the two snipe at each other between takes, camera-ready smiles pasted on as they hiss between their teeth, is deliciously awkward. But it also makes time to acknowledge the deep-seated—sometimes very deep—respect the two held for each other, even if it took Siskel’s death for it to become completely evident to Ebert and those around him.

The At The Movies era was arguably the most important phase of Ebert’s career, and Life Itself spends an appropriately sized chunk of time exploring it, via archival footage and interviews with producers and Siskel’s widow Marlene, among others. But it’s only a single chapter in the sprawling story of Ebert’s life, which the film skips through semi-chronologically, filling in the essential moments on the timeline, but finding much more fruitful material in the footnotes. The stamp he used to print his byline as a journalism-obsessed adolescent; the time he literally stopped the presses of the college paper The Daily Illini as a cocky, audacious editor; his stilted, disastrous first time on camera; him explaining Michael Apted’s Up series to his granddaughter as he writes a review of 56 Up from his hospital bed: These are the shadows and highlights that fill in the picture of Ebert as a person, not a Wikipedia entry. And they’re given further life by Ebert’s words, written in the book Life Itself and judiciously delivered via voiceover in the film by voice actor Stephen Stanton, who makes his voice sound just enough like Ebert’s to make the narration feel natural without tipping over into spooky.

Despite all that, the specter of death hangs heavy over Life Itself, which went into production when Ebert was still alive and relatively optimistic about the future. (A short scene where Roger and Chaz discuss the re-design of rogerebert.com, which didn’t launch until after his death in April 2013, is an especially meta bit of foreshadowing.) Watching that optimism fade over the course of the present-day footage in the hospital is gut-wrenching, particularly when James focuses his camera on the steadfast Chaz, who lets only the tiniest glimpses of fear and frustration peek through her resolute façade. Those glimpses are enough, though, to remind viewers that they are watching Ebert’s eulogy, one he helped author in more ways than one.

But Life Itself’s most powerful element is one Ebert had no control over: its context. Ebert was an advocate of context in criticism, and it would probably please him as both a critic and a fan of irony to know that his death is what enlivens Life Itself. Watching that context actually take shape onscreen is remarkable—remarkable that James had the premonition and audacity to capture it as he did, and that Ebert not only let him, but encouraged it. After 45 years of watching, critiquing, and loving film, the man knew what made a good movie.