I chose to read this book because the concept sounded really, really interesting, and captivating. And the concept itself is. But the book really isn't.
[Spoilers below. Watch out.]
First, here's a brief overview of the lore, from what I could tell.
The overarching story of American Gods is that Odin and Loki, two ancient Norse gods, crossed over to America with their people at some point. All the gods exist because of the people who sacrifice/believe in them. Basically, gods live on belief and die when they are forgotten. In American Gods, the old gods are "fighting" the new gods, which are the embodiments of modern life concepts such as the internet, the media, drugs, etc. But Odin and Loki are the ones who have incited this battle. Odin rallies the old gods, and Loki rallies the modern concepts, and they each convince their side into a giant fight with the other. Secretly, though, their actual plan is to thrive off the power created by this giant fight. Loki plans to throw a spear into the center of the fight, dedicating the fight to Odin, therefore making the whole fight a sacrifice to Odin and making him more powerful. This plan is thwarted at the end of the book, by the protagonist.
Next, let's get into the problems.
1: The idea of Gods being killed by other Gods doesn't make sense. We see Gods coming back from the dead briefly every so often, we see people coming back from the dead, and it's made clear near the end of the book that literally anyone can come back from the dead through some god magic means. Not only can Gods be revived, but they also shouldn't be able to die in the first place. There are gods in this book who die, not from being forgotten but from getting run over or shot. That doesn't really line up with how Gods are originally portrayed to work. At one point, Odin is shot and killed physically. But then he comes back as a ghost, around the end of the book when we learn about his plan. But what's the point of him getting shot if it didn't even affect anything? The fact that these Gods exist at all seems to prove that they have existing believers, and if they feed off of belief, then what does it matter if you shoot one or run one over? What even changes if you kill the physical body? The rules behind killing a god might have been explained at a very slow pace across this story, but the rules were definitely never justified. The fight between old and modern gods at the end of this book is hyped up from the very beginning, and yet not only does it never happen, but it never has a reason to exist in the first place.
2: About once in every chapter, there's a long passage that takes place outside of the story, sometime in the long distant past, in different parts of the world. They're short stories about the people living in those ancient times, who their gods were, and how they influenced their people. These stories are, I think, supposed to explain how the whole "belief fuels gods" system works in this book, as well as highlight the contrast between the gods then, and the weakened gods now in America. But the thing is, it's so frequently brought up that there is simply no need to reinforce the idea further than it is reinforced after the first couple of chapters. This book kills a horse at the beginning of the story and beats it until the very end when all that is left is horse pulp and a story that already finished itself. And it slows down this long story so much more when you have to read yet another short story.
3: For some reason, this book has a sub-plot of sorts which goes in a completely separate direction from the main storyline and doesn't contribute anything to it.