I read Lucifer's Hammer not long after it first came out in the late 70s. It was an early true survivalist/prepper story. Though it has some slow spots, and is a bit gruesome in places, overall, the story is engaging, and relatively realistic for the genre. I do not want to do any spoilers yet, until I know quite a few people have read it and have commented on it. It is definitely worth some discussion.
Just my opinion.
Jerry