"The sound and the Fury" is difficult. It can be confusing. Many essays are devoted to whether the difficulty is justified, but it is important to remember that it was not Faulkner's intention for this book to be difficult.
When interviewed about this book he explained the book's structure in terms of his attempt to try to capture Caddy's story without removing the intensity and bile from its telling by reducing her to explaining herself. This is why there are four narrative voices, each time Faulkner tried a different voice to tell his tale, and each time in his own words "failed". This is not a reflection of the skills of Faulkner as an author - the book is exceptionally well written, but rather probably has its roots in the reductive nature of language, which Faulkner found failed to capture the image he wished to pen. An appendix was added to the book in later editions and Faulkner suggested that this should be read first, as it explains the plot, the four narratives then serve to elucidate and add colour to the bare facts provided in this short "obituary" as Faulkner termed it.
Returning to the book. This is, i feel, Faulkner's most ambitious novel, and if he claimed to have failed in his telling of it, it does not show, this book is emotionally draining and moving in not only the story that is unveils, but also in the manner of its unveiling. There must be few who can fail to be moved by the pithy second narration, with its disjointed syntax which tells of its own despair, or not feel pity in the simplicity of the first.
thematically, this book is huge, covering sin, death, love, greed, envy, power.... life!