Some books are not meant to have any changes to fonts, size or reflow. "House of Leaves" is one example of a book formatted specifically for printed books which

Some books are not meant to have any changes to fonts, size or reflow. "House of Leaves" is one example of a book formatted specifically for printed books which does not translate well to ePub. (source: I read this book in epub) When it comes to preserving the intended layout, PDF simply translates better.