When I prepared to take my first SAT, I relied on this book to prepare. Let me first talk about the good aspects of the book:
It demystifies the SAT and takes a "student friendly" approach. That is, it helps convince the reader that the SAT doesn't measure intelligence, self-worth, etc. While this may or may not be true, it relieves one of a significant burden by believing that the test doesn't test anything innate, which prevents the formation of artificial mental barriers or blocks.
The vocabulary list is quite good, as it consists of a short, but sweet list of 200 words that are likely to show up on the SAT (either in passages or in the sentence completions). For such a short list, it sure does get a good number of "hits" on the real thing.
The math refresher is good -- it's not a math textbook in the sense that it will, in vivid detail, teach you the fundamentals of mathematics beginning with "2 + 2 = 4", but it does give you a great refresher of all the topics you (should) have learned. If you're shaky about performing basic algebra, then you don't need an SAT prep book -- you need a basic mathematics book. It also shows how these basic math tools can be applied to the SAT, by showing how to solve several "famous" or "representative" problems to give you a feel of the kinds of problems you'll likely encounter.
The grammar/essay sections are good, too. It goes over the fundamental errrors that you'll likely encounter without attempting to write the next great treatise in English grammar. So with the rules in here, you'll feel comfortable answering the questions on the real test. I went from a 650 (62 MC, 10E) to an 800 (80 MC, 12 E) simply by learning the rules given in this book's grammar section.
The best part, by far, of this book is the set of three very accurate, very SAT-ish practice tests. They're slightly more difficult than what you'll encounter on the SAT, but not by any significant margin. The math questions are sufficiently convoluted in wording and the content is great. The passages are of SAT level and the questions are very much in the flavor of the test. The writing/grammar questions are also superb -- any error that you can find on the real test, you'll find in this book on these practice tests. So, all in all, good practice that will demystify the content/format/questions on the test.
Now, for the bad:
Firstly, the reading comprehensions "tips and strategies" are just god-awful. This book explicitly states to "not read the passage and just skim it for the gist". Are you kidding me? That's how you miss out on big points on the reading comprehensions, especially the tone/overall meaning/theme questions. In fact, I was so naive as to follow their advice and got a lower score than I'd deserved (the first time I tried their method and scored 680CR, but when I retook and read through the passages without skimming, I scored a 760.) It's for this that I dock a star -- the section's called "critical reading", not "skim through and hunt for factoids which will invariably be out of context".
The book also doesn't have enough practice tests. The SAT is very much like any intellectual or artistic pursuit -- one's skill is directly proportional to the amount of practice that one has. And if you're using this book as your sole source of preparation, the three tests, while well designed, will run out quickly, and you'll very soon need to buy some more. For this, you can either buy PR's 11 practice tests or the Official SAT Study Guide which has 8 tests created by the ETS (guys who write the SAT). In this case, I'd go with the Official Guide -- no test can be as accurate as one written by the guys at the ETS. Not a huge downfall, especially since most people won't take that many tests, but it's nonetheless a caveat for those aiming for relatively high scores.
All in all, a very light and fairly entertaining read that will get you familiar with the SAT and help you raise your score. But if you're really serious, you're going to need to pair this with another book to provide an alternate perspective (I'd reccomend Barron's), as well as with the (New) Official Guide for practice tests.