Safdie brothers completism. What passes for romance amongst NYC junkies, and various kinds of codependency. Based on Arielle Holmes's experiences; she also leads. Caleb Landry Jones plays her somewhat disinterested love interest. The music is sometimes intriguing but otherwise there's not a lot to it.
Wikipedia has some details. Nicolas Rapold (and others) dug it. Godfrey Cheshire points out its strengths and flaws.