If the story is good enough, and I like the characters, I can forgive weak world building and plot holes. This was not the case with Divergent. I just couldn't stop going "but why...?" I also strongly dislike the sadistic, manipulative streak that comes out at the end. The heroine's boyfriend being mind controlled to attack her, the way she's set up so that she has to kill people she cares about. Combined with the utterly unbelievable world, I just didn't care for anyone in the book.