Many sci-fi fans consider Heinlein to be one of the genre's luminaries. That may be deserved, with titles like "Stranger in a Strange Land," "Have Spacesuit Will Travel" and "The Man Who Sold the Moon," but if this were the first Heinlein novel I had read, it would have been my last.
As books go, this one has all the things you're supposed to avoid. Pointless, gratuitous and unerotic sex? Check. Meandering story, resulting from an incoherent plot that never really goes anywhere? Check. Unresolved mysteries? Check. Self-indulgent asides and self-references? Check. While he manages to avoid the appalling racism of "The Fifth Column" and the equally reprehensible sexism of "Friday," the writer in this book fails to deliver anything that is worth reading.
Serious devotees of Heinlein's writing will enjoy the tie-ins to "Time Enough for Love" and "Number of the Beast," but for those looking to discover for themselves why Heinlein remains so popular today, or merely working their way through the science fiction collection, this is a book best skipped.
Half a star.
If you enjoy science fiction, I'm sure you've read Heinlein. But if you haven't, then get started! However, don't make this your first Heinlein book. This story links to (probably) a dozen Heinlein stories, and if you haven't read at least some of them, you'll be lost before long.
If you are familiar with "The Moon Is A Harsh Mistress", "Time Enough For Love", "Stranger In A Strange Land" and "The Number Of The Beast", add this to your reading list and enjoy!