The story revealed in this book could be very interesting and full of new ideas. However, the author is incapable of doing so and resorts to abandoning what he began. There is no need to get into the past of Oskar's relatives. While there was a theme for it in books like The Brief Wondrous Life of Oscar Wao, a theme between generations is absent here.
Furthermore, I'd like to reveal some recent ideas when writing modern english. After a small idea or setting is introduced and concluded in its description, it would be useful for the reader to have what is called a paragraph break. This is when one takes the first sentence of a new idea, and rather than attaching it to the previous idea, puts it a line below to let the reader know that there is a transition of ideas occurring. This is very different than a page break with one sentence of none on it. Imagine if all of those one page sentences were condensed into one page, with paragraph breaks in between. It may look more readable. In its current state, this book is uninviting, regardless of how well it's written, due to poor structural choices in formatting.