This piece of literature will show up on any top lists of post-apocalyptic literature or classic science-fiction. It came up on a related search for "Lucifer's Hammer" for me.
Amazon has it rated under customer reviews as a 4.5 out of 5 stars based on almost 700 reviews.
Here is what Amazon has to say about the book in its description:
"Alas, Babylon." Those fateful words heralded the end. When a nuclear holocaust ravages the United States, a thousand years of civilization are stripped away overnight, and tens of millions of people are killed instantly. But for one small town in Florida, miraculously spared, the struggle is just beginning, as men and women of all backgrounds join together to confront the darkness. "
About the author, Pat Frank, Amazon has this to say: