It's really hard to describe what the book's about. It's an epic, through and through, and all epics are hard to detail precisely. Inter-generational trauma? Handling one's "sin"? Making a livelihood after repeated failure, be it yourself or external factors?
Contrary to my first sentence, there is one character that I would describe as pure evil. But I feel that just supports one of the conflicts; however incredibly rare, what can an individual do when they come across a bonafide force of evil?
It is dripping with Biblical imagery, and Steinbeck's prose is rambling and tangential for some (though poetic for me), and his characters are not "realistic" and larger than life (but that's what makes them pop off the page for me and so memorable. I guess it's always a balance).
"Now that you don't have to be perfect, you can be good."