So many things. The dialog was mostly atrocious; the villains sound so blatantly, stereotypically villainous, as if their lines were pulled straight from the Villain Writing 101 textbook, and in fact, so many of the characters sound like tropes of their various character types. The sniping between Wisty and Whit is annoying. The random point-of-view switching between Whit and Wisty is confusing. There is really very little character development at all.
One of the most annoying things, to me, is the authors' reference to musical groups, authors and books, and celebrities - but changing a letter here, a word there, to create fictitious celebrities, etc. In fact, my edition of the book had an actual index of these items, "provided" by the New Order as a list of banned books, musicians, etc. Especially egregious examples: "The Pitcher in the Wheat"; Irish band B4; artist Margie O'Greeffe. I mean, why? What was the point?