I have read it several times. As for racism, he describes the reality of living in a segregated society, regardless of whether the segregation is de facto or de jure. I see the book as intended to subvert the worst of racist attitudes, but all members of such a culture are scarred and influenced by it and the author definitely has biases.

Edit, I have no doubt that the author is himself racist. But his intention and depiction is community between people of all colors and races. Given his era, for me, that is enough good faith and positive intent to not cancel the book.

I would contrast Lest Darkness Fall by L Sprague de Camp which leans into racism in an entirely unnecessary way, inserting it anachronistically into a plot about ancient Rome.

I agree. It is an excellent apocalyptic book.