The Odyssey by Homer (I actually read this in an anthology but this is a stand alone version with the same translation/translator)
One thing that surprised me on reread is how little of the epic really deals with Odysseus's adventures. While the epic is divided into 24 books, Odysseus doesn't even make an appearance until Book 5, and then ends up telling the story of his travels at a banquet. His descriptions of his interactions with the cyclops, Circe and various other legendary creatures take up less than seven books. The majority of this is really about Odysseus's return home, and his interactions with the suitors, leading to their eventual deaths.
One other thing that really stood out to me is that Odysseus is known for his intelligence and cunning but many of his decisions are kind of dumb. It seems like every time he lands somewhere and explores an island, bad shit happens. However, his curiosity overrides his decision making skills, and every new island leads to new explorations, and more death for his comrades. He also doesn't share information very well - at one point, he is almost home when his crew open a bag holding the winds because he never explained why they couldn't open the bag and they suspected he must be holding out on them and hiding gold and treasure. Of course, there wouldn't be much of a story if Odysseus had made it home in a year or two. I also felt kind of bad for the cyclops. He didn't obey the Greek rules of hospitality since he started eating the men in his cave but can you blame him? The guy comes home after a long day of goat herding, only to discover some guys in his cave who have eaten some of his food and have the audacity to demand gifts because he is now their host, according to them. I mean, I wouldn't eat anyone, but I would definitely be kicking some people out and calling the ancient equivalent of the cops - or a locksmith.
However, I still thoroughly enjoyed the story, even if it is harder for me to see Odysseus has a hero - instead he is a flawed protagonist. It also teaches things about the past, such as the ancient concept of hospitality and how people once viewed their gods. I hate to admit this, but my first interaction with the full Odyssey story was in a Disney comic book/graphic novel with Odysseus portrayed by Donald Duck (definitely a good choice for the impulsive part of Odysseus's nature - I can't find the actual edition, I had but this sample should give you an idea of what the comics looked like), so even now, twenty years later, I have a hard time picturing anything other than a talking duck in my head when I read The Odyssey. I'm just glad I never had interactions with the Wishbone series as a kid because who knows what would be going on in my head then when reading classics.