Can't add much to the great reviews, only I'm from the South (MS) and my mother, aunts,..others informed me of such an issue when I became a grown man and ended up back home for a few years.
That said, there isn't a wasted performance, line, scene,... in the entire movie, just a steady paced Southern Tale of Reconciliation.
Others here give the bigger nod to the Aunt, mine is reserved for Mr. Steady (Duvall), if you want to see pure genius in ONE scene, find the one when he takes the letter and reads it to his (back sliddin) Daddy.
The emotion he emits in that scene is simply compelling. It's a movie for grownups, for I don't see a youngin being able to sit through a Movie with no (REAL) violence, bombs, tight skirts, short-shorts, fake boobs/foreheads/eyebrows,...Two other good scenes: Duvall and his older (black) nephew, telling him how he found out "Life Ain't about you,..." and the Blind Aunt telling them of Duvall's birth.
Great Movie, start to finish.
A solid 4 Stars, actually a few 10ths more, not quite enough for 5, because it's not "edge of your seat" but a VERY good movie.