Continuing some thoughts on Twilight's success: I think that many novels become popular because they play out a reader's secret fantasy (Harry Potter : I want to be a wizard! ; LotR: I want to be a returning king!) But the good thing about those novels is that they go deeper. You may start reading because it fulfills a personal fantasy, but the author uses the world/characters to examine deeper themes and ideas and concepts and emotions and characters and such. Twilight DOES NOT do that. It is just a fantasy on page.