This is a great book, if you are too lazy to even walk around in Riven. I had completed everything, except for 2 of the last 3 puzzles, and all I wanted was a couple of general hints to point me in the right direction. Instead, the first half of the book, which is supposed to do just that, was more of a smoothed out walk through - not every step, but it pushed you through the whole game and revealed all of the secrets and solutions. The real walkthrough in the back is basically the same thing, just bulleted and put into command sentences. Don't buy this book if you want to take your time and figure things out on your own. If you just want to beat the game quickly, with no respect for the beauty of the programming and the story, this will do fine.
On the brighter side, after I bought this and read it, I stopped hitting my head, solved the puzzles again for myself, and finished the game in 2 hours. I would still be playing around in the ceremonial chamber and with the marble puzzle if I didn't get this book. I missed the small things, which made so much difference, and I couldn't make the connections, which is what this is all about. Please, try Riven on your own first, and if you are really stuck (I mean really), then get this book. It will alleviate your headache.