I feel very conflicted about this book. It's one of the ones that I've re-read every year or two; it's large, and once you start it it's very hard to put down. Heinlein, whatever his faults, was a storyteller - and a gripping one.But his faults are largely on display in this book.When I was a young teen, my brother and I used to torture each other by reading particularly ripe and painful passages out loud to each other. This book, and the "Notebooks of Lazarus Long" excerpts from Time Enough For Love, comprised our list of pain. They were truly retch-inducing.But that damned Heinlein really WAS talented. Witness the fact that I've read the book more than ten times in the past couple of decades.The flaws are many? He gets really creepy on the sex. The "old man Heinlein" voice is particularly noticable - it's a bit jarring and weird for everyone to banter and quip like someone from Kansas City in the 1930s. The incest angle gets really sickening, to be honest - why does he glory in it in so many books? I have to wonder.And towards the end the whole thing basically falls apart. I'll avoid spoiling it, but basically reality sort of falls apart and things just get weird. There are lots and lots (and lots and lots) of obvious in-jokes, some of which I get, and some of which I don't. That gets old and tired after a while. I'll also say that there's something of a loss in the book; it starts out first-person in the voice of one protagonist, but then starts rotating between viewpoints in each chapter. Towards the end, when the original lead is "speaking", it feels as if he's somehow lost. They're all just merging into a single Heinleinian superman/woman.Which reminds me of a parody of Heinlein that my teen-aged self wanted to write, come to think of it. His later characters are all sex maniacs, and all act, think, and talk the same - like an idealized Heinlein, I presume. If he hadn't had a gift for storytelling on a par with that of Rudyard Kipling, he would never have gotten away with it.I've gone back and forth on this book. I hated it the first time I read it (shortly after it was first published), warmed up to it again...and now, decades later, I find myself more repulsed by the sex and incest angles than I used to be. Maybe I'm just getting old. Nonetheless, I'll likely end up reading the book again in another year or three.