Kill the Poor is a prime example of a failed adaptation. Not that I've read Joel Rose's novel, which is currently out of print, but I have read what the film's director, Alan Taylor, has to say about the book, and none of his words could be used to describe the version that he delivers on screen.
First of all, he calls the book "hilarious". The film doesn't even seem intent on being so. He then goes on to label it "tragic" and "a whirlwind", neither of which applies to his film, which has no emotional ground whatsoever. The characters are undeveloped, their story is boring, and the plotting is a mess. Surely these elements are handled well in the novel and surely there are other assets within its pages, but there is really no evidence of its merits here. Based on the film, I was uncertain as to what about the book was worth Taylor's "yearning to adapt it.".