If you are serious about getting into top B school then 15$ is a trifle amount for this book. Although book itself does not have many excercises but the online material that comes with the book alone is worth more than 15$. This book has some tricks which I couldnt find in most other books and since Sentence correction was the only department where I wasnt scoring correctly over 95th%, I had to get this book.
With this book you can take 3 online CAT exams. To give you an idea I took the third exams 1 day before GMAT and got 760 in that. Guess what my GMAT score was? 760.
In the end if you are serious about getting top score you should get this book.

I bought the whole set based on some posts I saw at a GMAT forum along with the Princeton Review GMAT books, and the Official Guides.

After doing all three of them, I've this to be the most disappointing. There's a couple of reasons:

1) there's some typo errors, which should be fixed as this is a study book

2) there's questions and sometimes even entire passages copied STRAIGHT out of the Official Guide. I'm not sure the copywrite law on this but it was really tedious since I already went over the OG. Also, it was a waste of my money to have bought both the sets.

3) the explanations are mediocre at best. There's also little follow-up and in depth explanation.

4) The level of the questions were too easy. If you're looking to boost your 500 to a 600 this book might help. If you're looking to get a 700+, these books have almost no material dealing with that diffculty.

Either way though, if you have the official guides (11th edition), you basically have these books

The most annoying of all in this book are the examples cited. This book claims to be edited, tested by people who scored 99 percentile on GMAT and still there is no originality! All the examples are cited off from the GMAT verbal workout or from GMAT review 11th edition. After each concept an exmaple is cited which we cannot attmpt as there are no choices available. The book goes on and on as to how to correct the sentences which is not the case in GMAT. We are not taking the test to correct it, we taking the test to pick the best of the options and to score it. In short, though this book is strong in concepts, I would not spend $16, rather would prefer to buy Kaplan Test book or GMAT Verbal workout, etc. Anyways you will endup buying books from GMAC for sure...

This book is great! It concisely covers the main types of sentence completion questions and completely demystifies this tricky, often confusing portion of the GMAT. The book is easy to understand and provides lots of examples and practice questions. One caveat: a lot of the practice questions refer to the 11th edition of the Official Guide and the Verbal Official Guide. However, this book can definitely stand on its own. Another major plus: when you purchase any of the GMAT prep books and register the book on the GMAT Prep website, you get e-mails with useful articles and suggestions for studying. These articles were really helpful. In particular, an article on pacing was a lifesaver. I highly recommend this book.

I bought this book to practise more and liked that there was a seperate book for each GMAT section. But, I was shocked to see that there were no practise exercises in this book. This book (and the other book I bought in the series) refers to 2 different books for practise exercises!! If there is need for fair disclosure, it is now!! I now have to go through the pains of returning the 2 books!!