In particular, the first section, whose narrator is the severely disabled Benjy, failed to ring true for me. It seemed to me to repeat the fatal problem of The Red Badge of Courage, in that the writer's voice is far more sophisticated than his character's thinking could possibly be. Very specifically, I observe from my own daughters that they are much more interested in their own emotional state than in observing what other people are saying or doing around them; Benjy, as portrayed by Faulkner, is completely the opposite, and I found that so contrary to my own experience that I could not engage with the story at all.
(I also didn't really like the racism of his characters being displayed but not really interrogated, but I'm also reading Huckleberry Finn at the moment which is rather worse in that regard.)