If on a winter's night a traveler begins by addressing the reader:
It quickly becomes apparent that the narrator is not, in fact, addressing the reader, but is instead addressing the protagonist of the novel, the Reader, who is addressed in the second person as 'you' throughout the novel.
In the odd-numbered chapters, we are told the story of the Reader attempting to read a novel--at first, If on a winter's night a traveler by Italo Calvino--but never quite managing to get through one; he always reads just the beginnings of books, which are given in the even-numbered chapters. Each new novel is generally purported to be the same one which the Reader has just been reading, but bears no resemblance to it, telling a different story in a different style and genre. Each story, though, does tend to share some themes with previous stories, or have other similarities. For example, after a story in which mirrors feature prominently, later stories feature mirrors, or doubles, or something metaphorically similar, and several stories involve the protagonist trying to find a way to relate the inner world with the outer--or trying to separate the two.
Eventually, the plot involving the Reader begins to make some sense of the succession of initial chapters, and the Reader gets involved in a plot of his own, featuring love and danger and all one might expect from a story in which the Reader is the protagonist.
The novel is quite self-aware; it addresses the protagonist, the Reader, as 'you' (though the narrator will address another character as 'you', at another time), and we, the readers, are given to wonder if we are meant to identify with this Reader, and if the 'you' of the narrator is addressing us or the character. And then, too, there is the question of the narrator's "I", which is addressed explicitly in the second chapter, which is (supposedly) the first chapter of the book the Reader has just purchased--If on a winter's night a traveler by Italo Calvino:
The plot of the odd-numbered chapters turns on the mystery of how all these misprinted books came to be, and whether the Reader will ever get to finish a book.
I enjoyed the first half of this book rather more than the second half. The way the book is put together, the writing, the themes building on each other in unrelated stories, all that is really excellent. And the experience of reading chapters addressed to a Reader who is 'you' but is not you works very well, too. But, as the plot begins to unravel (at least partly) in the second half, it lost a little of its charm. Some of it was just obscure for the sake of being obscure--which is appropriate, given the plot, but its appropriateness didn't give it deeper meaning. Or, its deeper meaning was really something shallow. And it began to feel like the plot of the odd-numbered chapters was dragging on--though this was perhaps intentional, given the way things very suddenly wrap up at the end.
If on a winter's night a traveler is certainly worth reading, if you want to see a book make excellent use of some literary tricks.