This book, like many posthumous `collaborations' that are attempts to complete an unfinished work, has both good and bad things about it.
First, yes, Heinlein's touch is definitely evident, mainly in the basic story setting and its main characters. Clearly the outline and notes that Spider worked from defined these elements unambiguously, and anyone familiar with Heinlein's work will find much here that will evoke that feeling that so many of his YA books from the fifties had. The story is very definitely set in the `Future History' line, with references to Red Planet, If This Goes On, Coventry, Time for the Stars, Starman Jones, Space Cadet, and multiple other stories. Its protagonist is, at least at the start of this book, a rather typical Heinlein older teen, a young man who starts with no clear idea of what he wants from life, and while quite intelligent has a tendency to leap without fully considering all the consequences.
But it is also true that this is Spider writing, and as such it's told in Spider's voice, with his own very distinctive style, which includes his penchant for punning, and to some extent, mysticism, neither of which Heinlein would normally touch. This is not necessarily a bad thing - I've enjoyed many of Spider's other books, and his style normally complements his story material very well. But here I found some of this a little jarring, as it simply didn't match my expectation of how Heinlein's voice would have told this story. Not that Spider either should or could have really matched Heinlein's voice - any attempt to do so would have probably been a disaster.
The objections some others have raised about Spider inserting some commentary about current events into the Future History time line (as `The Terror Wars') I found was actually fairly well done, giving a more solid basis to the rise of Nehemiah Scudder than Heinlein ever did (though this was an area that Heinlein himself avoided, as too depressing to write about). Spider does manage to create characters that I could fully believe in, and they bear a strong resemblance to what these characters would have been like under Heinlein's pen, and this does much to keep this story highly readable and enjoyable.
But I found that the direction of the plot for about the last third of this book rather upsetting, as it plays havoc with the Future History as we have come to know and love it - and this area is pure Spider, for as stated in the afterword, Heinlein's notes were incomplete, and did not include an ending. The ending that is here has both a deus-ex-machina device (but one that Heinlein himself used in one of his other stories) and a clear path to a possible sequel, as clearly there is more story to tell, if Spider (and the Heinlein estate) would so desire.
I finished this book with very mixed feelings. Yes, it's another entry into the Future History corpus; yes, it's well written, engrossing, and enjoyable; but no, it's not Heinlein, and it branches in a direction well outside the known Future History, at the very least requiring another major branch in the World-as-Myth world view. But if Spider ever does write a sequel to this, I'll be there at the bookstore waiting to buy it when it comes in.
--- Reviewed by Patrick Shepherd (hyperpat)