At the outset of I’m Still Here, Joaquin Phoenix laments, “I don’t want to play the character of Joaquin.” And cue the wry laughter from knowing viewers. After all, that’s the big question about this “documentary” directed by Phoenix’s brother-in-law Casey Affleck, and indeed about Phoenix’s entire life since he announced his retirement from acting in 2008, ostensibly to pursue a career as a hip-hop artist: Is it an elaborate Andy Kaufman-esque hoax?

I’m not sure which answer makes I’m Still Here a better movie, though one certainly makes Phoenix less of a jerk. Affleck follows Phoenix as he impulsively breaks the news of his job change on a red carpet, then tries to launch his music career by convincing Sean “P. Diddy” Combs to produce his record. And along the way, we watch him become progressively more unhinged and abusive to those around him, all while resembling Zach Galifianakis in a remake of Reservoir Dogs.

It’s hard not to suspect this is all a grand parody of self-absorbed celebrity dilettantism, with scenes of Phoenix in hookers-and-blow revelry before spinning out numbingly banal rap lyrics about how hard it is to be famous. But that still leaves a lot of time (before and after his infamous 2009 Late Show with David Letterman appearance) spent with a guy who’s spinning out of control, berating his assistants and assaulting hecklers. Whether Phoenix is a douche bag or a “douche bag” is a question that makes for some frustratingly one-note cinema.

There are certainly some effective moments, including one with Combs — who, if he’s in on the joke, plays it perfectly — listening to Phoenix’s CD for the first time and when Edward James Olmos provides Yoda-like philosophical guidance for Phoenix. Truth be told, if Joaquin is just playing the character of Joaquin here, he could have used a better script.