One thing which cannot, I think, be expressed frequently enough is the immense impact Don Quixote had on modern literature. If we think of literary devices like accessories on a car, then Don Quixote is the pimped-out Caddy of books. I can truly think of no work which approaches it in either innovation, nor actual use of technique. It would be an amazing enough thing if an author today attempted to weave multiple narratives, stories within stories, and epic adventure within one cohesive work, but for Cervantes to have done this without the benefit of a massive number of books having already attempted similar things is nothing short of phenomenal.
I cannot think of any non-poetry work of fiction which has withstood the test of time to the extent of this book. As I was reading it, the only book(s) I have read in recent times which reminded me somewhat of it was Stephen King's Dark Tower series, for Don Quixote actually acknowledges its author, Miguel de Cervantes is a person in the real world. It's self-awareness in that sense is therefore similar to King being a character in that series of books.
Like so many writings of old, there are concepts which are outmoded and would be offensive to most modern readers as well as to Muslims. There are numerous patronizing statements regarding women, Sancho Panza dreams of selling Ethiopians into slavery. There is the customary medieval Christian habit of insulting Islam. I speak of these only to ready the prospective reader. None of these issues, however, can detract from the extraordinary quality and readibility of this masterful work. It taps into every emotion over the course of its many pages. It has some truly funny moments, and I cannot help but suspect that the impact, if it were read in its original tongue rather than through a translation, would be even more intense.
Cervantes refers to this book as a "true history" throughout it. He refers, somewhat mockingly, to Don Quixote as an invincible knight when he introduces the chapters. As indicated above, he gives a brief description of the contents of the chapter when it begins. So, we have the example of "Chapter XX: Of The Unexampled And Unheard-Of Adventure Which Was Achieved By The Valiant Don Quixote Of La Mancha With Less Peril Than Any Ever Achieved By Any Famous Knight In The World." In this, we have the sarcasm. When Quixote's friends discover his madness, they look to burn his books, but save a few good ones, and one in particular by Miguel De Cervantes is saved from the fire because the "author is a friend." This is an example of how the book is placed in the world alongside its author.
During the course of the adventures, a book, "The Man Who was Recklessly Curious" is discovered in an Inn by a priest and his companions and is read in its entirety. We discover a seducer of a wife called Lothario within it's pages. This name for a seducer later is brought to even greater fame thanks to Nicholas Rowe's The Fair Penitent. Here we have one example of the story within a story.
We have multiple viewpoints, as there is the omniscient narrator, along with multiple first person narratives being told by characters, in addition to the fiction within the fiction. The book itself, purporting to be a true history, refers to the historians interacting with events as they observe Don Quixote and parts of the history being lost, and descriptions of how portions of that history of Don Quixote are subsequently found. References to the specific historians who chronicle Quixote are included as well. Because of all this complexity, this is a book which should be read both carefully and repeatedly.