I chose The Grapes of Wrath partly because I was fascinated with the Dust Bowl of Woodie Guthrie's America, partly because it had been lying around in my book shelf for way too long. I imagine that The Grapes of Wrath would be an unbearable read for someone who is not previously familiar with the history and decade in question. Steinbeck does a brilliant job of interspersing the story with vivid descriptions of life in rural America, but these might lose some of their brilliance if the reader does not understand their context. And you really should consider doing some serious Wikipedia research before reading.
The Grapes of Wrath was an extremely enjoyable experience for me, but I can't really articulate why. In a different state of mind, I might have hated the nitpicky plot points and plodding character arcs. Rose of Sharon was painfully obnoxious in every scene and the realist affiliation made some developments seem obvious. Yet there is something both magical and romantic in the way that Tom Joad drives the family through desperate and dangerous acts. A sort of purity of spirit follows the characters as they act on basic human needs.
For those who can afford the time to truly immerse themselves in the Dust Bowl era and the Great Depression, The Grapes of Wrath is a true masterpiece. It is brilliant to the point of giving me goosebumps and sad as to make me cry. The story of social inequality and injustice is just as relevant today as it was when this seminal work was released.