From a post by Jason Pettus over at 400 Windmills:
As my own life has transitioned over the last ten years, though, into one of writing for a living myself, I have of course found it more important to do go back and read more classic literature, which was the whole impetus behind asking Bud if I could join 400 Windmills in the first place. Which is great for a second reason as well, which I can't emphasize enough to the younger visitors to this site; namely, how much more appreciation I have for older books now, the older I get and the more world experiences I accumulate. Thinking about it yesterday, I realized that I probably wouldn't have liked DQ if it had been forced on me in high school, but now I'm astounded by what a savvy, jaded yet optimistic view of the world Cervantes posits in the novel. He mocks noble virtues on a page-by-page basis, even while quietly championing some of them as well; in doing so, he basically strips away the artifice of etiquette and fake moralizing, the fairytale of revisionism and radical politics, and basically says, "Look folks, here's how it is. The world is rough and complex and many times the lines authority figures hand you are complete BS. Yet there are certain little parts of it that are usually true, too, as long as you take the time and smarts to examine the situation yourself." [...]
It's a difficult worldview to maintain sometimes, and definitely one that a lot of people would rather not consider: that Republicans are actually right sometimes, that terrorists sometimes have good points to make about their anti-Americanism, that all those people in the world who piss you off also have nuggets with which you agree. In a nutshell, that the world exists as a series of grays, not in black and white, which 1) not only is a fairly modern idea; but 2) tends not to be a very popular one. Which I guess is the double surprise of reading DQ in 2005, that not only is it a thoroughly modern book that is highly entertaining on its own, but also that the book would remain this popular for 400 years in the first place. Cervantes, when all is said and done, is preaching a fairly subversive message in DQ, which is what led me to thinking of him in the modern world in terms of "The Simpsons" or McSweeney's; he's saying basically that everyone is a liar, that everyone makes mistakes, that even the craziest members of our society still sometimes have very good things to say, and things that they believe in that we should believe in ourselves. This usually is something the general populace seems to not want to hear, so it really surprises me that the book has been as popular as it has for as long as it has.