Harry Potter and the Half-Blood Prince by J.K. Rowling
I was seriously disappointed by Harry Potter and the Half-Blood Prince. Nothing happened. Well, until the very end, but even then, it wasn’t enough to save my overall impression of the book from being primarily that it was boring. They get a new professor, Dumbledore is all cagey with Harry, Snape is an asshole, Harry is an idiot, blah, blah, blah. Yes, I know there actually was a lot that took place in the book, but it still felt largely like it wasn’t there for anything other than setting up the last book.
Did I mention that it was boring?