I'm pretty sure if you don't at least know of Don Quixote de la Mancha, you have spent your entire life pretty isolated from any type of culture. I'd never read any of this before but I still knew that he was from Spain and was under the delusion that he was a knight errant and was therefore bound to rescue damsels in distress, right wrongs, vanquish giants and evil magicians, etc. I knew about his eccentricity and seeing things not as they were but as bigger and mightier so as to be worthy adventures of a knight errant (tilting at windmills that he sees as giants being the most commonly referenced one). I'd heard of his lady, Dulcinea, and his squire Sancho. Most of what I'd heard about comes from the first half of the book and seems to be the main story people know. There were other side stories in the first half that only tangentially involve him but for the most part, it was following his journey as he tried to be knight errant he thought the world needed, no matter how misguided he was. It definitely had humor but was also sad watching this madman trying to deal with the world as he saw it.
The second half was awful. Almost the entire thing consisted of Don Quixote and Sancho falling in with people who had read the first part of their adventures and using his malady to play pranks on him for their own amusement. It lacked the whimsy of the first half and I found it mostly to just be meanspirited and not fun at all.
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