Sylvester Stallone executive produces -- meaning approves or disapproves -- the documentary examining his own life and work.

That's red flag number one. Even in an age of ubiquitous "documentaries" (they used to barely exist in the margins of filmmaking), such a project should aspire to illuminate its subject, warts and all.

Here, Sly makes an attempt at a mea culpa, lamenting how he should have spent more time with his family, yet inclusion of that family's story scarcely exists. I had no idea his son, Sage Stallone, had died in 2012 at age 36. And the only reference to that here are life dates shown on screen after the brief segment about Sage appearing in the ill-received Rocky V.

And what about Stallone's other son, Seargeoh? Yes, that's right, Stallone had two sons, and Seargeoh apparently was diagnosed with autism at the age of three. Not that the documentary reveals that -- Seargeoh is never even mentioned; I found out only by searching online, and only after an image of the actor Milo Ventimiglia (who plays Rocky's grown-up son in 2006's "Rocky Balboa") inexplicably appeared beside the name "Seargeoh Stallone" when I Googled it. Try it. You'll see.

The real Seargeoh, apparently, has lived most of his life with his mother, Sasha Czack, now Stallone's ex.

Okay, maybe it's to protect the privacy of his children, and that's fine. But it's a conspicuous absence in a documentary ostensibly about a man's life. Which it is, to a large extent, especially about his childhood, and how his physically abusive (Sly implies this, though never directly says it) and "brow-beating" father may have pushed him to seek external validation from an audience, or crowd.

But the picture really focuses on the work, the ups and downs of Stallone's career, his regrets and his massive successes, and the way his two big franchises, especially the Rocky narrative, are really mirrors for his own life and career. Where this gets the most interesting, at least for this viewer, was when Stallone described these two world-famous characters as ends of a spectrum. Rambo is the broken hero with no home who dies alone. Rocky embraces humanity, and family, and is in turn embraced. Stallone admits he's both characters.

In "Sly," I appreciated this emphasis on the work. I make my own living as a suspense writer, have worked in film, and in my own much smaller and less famous way, have experienced a lot of the frustrations and joys. Every artist does, really. This telling of Sly's life seems like a letter to all artists, that they may aspire to such greatness at their own peril. That even with great success they may, like Sly, be left searching for inspiration, hoping to slow life down, hoping for another good fight.

I'm only going to compare this documentary to Arnold Schwarzenegger's because it is brought up so prominently in both of them how competitive they were. How toe to toe they went in the 80s making bigger and bigger action films and getting larger and larger grosses (not to mention biceps).

That said, Arnold's was better. I preferred Schwarzenegger's because it went deeper into his personal life and even his faults as a man and a husband.

Sly, the documentary, was good. But it mostly focused on his career. After the obligatory stuff about how he grew up and what a sonofabitch his father was, it was all about the movies. The hits and the flops. I'd've liked to have heard more about his marriages and his relationship with his kooky mother (which is completely overlooked) and especially about losing his son. Even his other business adventures are ignored. Wasn't he an investor in Planet Hollywood? We hear nothing about that.

Anyway, I enjoyed this. It was the perfect airplane diversion as I killed 7 hours over the Atlantic. But like the Arnold doc, I think Sly's life deserves more than a 2 hour recap. I could have handled at least twice that as long as the second part dove deeper into the man himself.

Sly may not be a deep dive into Sylvester Stallone's career but it's an emotional and engaging look into the life and career of a superstar on his own terms. Even if it can't cover everything it still hits the major milestones (and Expendables) whilst still having time for Stallone to acknowledge his own flaws and regrets.

There've been so many jokes about Stallone being an unintelligible muscle man so it's nice to have this to set the record straight. He's a really insightful actor who's put so much of himself in his movies. There are a few times Stallone's decisions and refusal to back down created some of cinema's best moments as well as some missteps he acknowledges which shows how far he's come.

Just as engaging as the anecdotes about filmmaking and how Rocky in particular was created are his observations about life. The pain, the loss and the speed it goes by are all discussed in a very frank manner with some heavy yet beautiful quotes that remind you Sly has a real way with words, in life and on the page.

There's also a great selection of interviews with other people in between Stallone's discussions, some who make perfect sense including Frank Stallone just generally being the best and Arnold Schwarzenegger getting to offer some funny stories about their infamous rivalry as well as others who are just cool to see (Quentin Tarantino!).

Thom Zimny's direction is great overall. Swapping effortlessly between the interviews and archive footage throughout with a generally nice vibe that means you don't want it to end. It only briefly falters in a few moments where it distracts from Stallone's openness by shaking the camera too much in an attempt to get as close as possible.