“Acting is not creativity, it’s doing what somebody else tells you to do,” Joaquin Phoenix declares in I’m Still Here, a film that charts his decision to stop being a thespian, grow a massive beard and rediscover himself as a rap artist. Is he crazy? Contradicting his own soundbyte with the most intriguing performance of his career, the answer is a resounding no. The story Phoenix and brother-in-law Casey Affleck have crafted is not insane, but assured – a fascinating study of self-identity.