Faulkner is often regarded as a "difficult" novelist, and this book is indeed a densely dilineated, complex tome. It is also, however, incredibly straighforward. It is one of those texts that you just have to go with. Too many readers approach this book with trepidation, because they have been told they are not going to understand it. Turn loose of your preconceptions about fiction and about narrative, and you will be amply rewarded.
Faulkner, along with Joyce, was a master of stream-of-consciousness narrative, and this is his masterpiece in that regard. To appreciate such a technique, you must as the Beatles exhorted, "turn off your mind, relax and go downstream." Go with the flow, no matter you noxious that sounds these days. If you let yourself think for a while as Benjie does, the whole patchwork makes perfect sense.
This is a family novel, more than anything else, but it is obviously not about the Waltons. Faulkner made a career out of delineating the disfunction of not only Southern families, but of the South itself in the era following its ignominious Civil War defeat and surrender . The whole social structure broke down from within, and though no apologist, Faulkner was enough of a realist to depict the society in all its infirm decline.
Southern revisionists can come along and deny its accuracy, but for a true picture of ther region in the first half of the 20th century, Faulkner is more accurate than any social historian.