It's a bit biased of me to say, given my passion for video games, but Indie Game: The Movie is without a doubt one of the best documentaries I have seen in recent years! Yes, this is a movie on Steam, but that oddness in no way makes it any less worthwhile and actual is rather a good thing as it makes it easily accessible to the millions that use the service.
Though other games and developers are touched upon, Indie Game is by and large the story of three of the most acclaimed and outspoken indie developers of the last decade: Phil Fish (Fez), Jonathan Blow (Braid), and Edmund McMillen and Tommy Refenes of Team Meat (Super Meat Boy). Through the years leading up to the release of their respective games, Lisanne Pajot and James Swirsky's film offer a look behind the curtain at the trials and tribulations of independant game creation, and provides a welcome perspective to what at times can seem nothing but praise and accolades with little thought given to just how much work was required for these games to see the light of day.
What it does best though is show that these are just normal people doing what they love, and at the same time make it incredibly easy to relate to them. Given their often brass and controversial outward statements (Phil Fish perhaps most among them), it actually came somewhat as a shock to see them in a more personal light away from the press, while learning their stories which were both engaging and even heartwarming having grown up with similar experiences. It's no understatement to say my opinion of them as both creators and persons was drastically changed, and I feel those so quick to anger at what they may have said in the past really ought to take the time to watch this first.
Whether you are a gamer or not (though I'm guessing you are, given where this is posted), Indie Game: The Movie deserves your attention. It's a fascinating look at indie game development and those involved with it, not to mention fantastically edited and accompanied by a great score by indie favorite Jim Guthrie. It won't take much of your time, but could very well completely change your outlook on this medium we all enjoy so much.