Not convinced

I tried putting in the time on this and actually trudged through 100 pages (twice as far as I usually go with a book I'm not impressed with) but I just couldn't get into it.
I admit that Steinbeck has a literary style all his own and it's decent, but the characters seem flat; the dialogue is atrocious; and the reader's sympathy is constantly confused: who are we rooting for?

Seriously, why is this so famous?