If it hadn't been for a misbehaving Kindle I would never have picked this book up. And that's appalling because I love Steinbeck's writing and I can't believe I wasn't made to read this in high school.
Sure, it's a rather convoluted tale with heavy Genesis (so, Christian) underpinnings, and this might irritate some folks. But that doesn't mean it can't be read as a metaphor for people, in general. All of our shortcomings, triumphs, ideas, tragedies... what makes us human to begin with.
There is no grand epiphany in this story, but instead there are multiple ones for each character. Adam has several, and is served in that by Lee and Samuel-- who can't be snakes, so are they the guardian angels of Eden? You could say Kate is a snake but Steinbeck kind of makes her a mix between the snake and Cain.
Enough of trying to understand the metaphors... the best part of the book is how Steinbeck tries to describe the grand scheme of human thought. It's almost as if he's written 600+ pages in order to write 20 pages about why we're always trying to figure things out. Things that are just going to be the way they are, but thinking about them gives us a modicum of control.
I haven't read any in-depth analyses of the book, and I don't really want to. It's clearly a book I have to spend a lot of time, well, thinking about.