The Official Guide for GMAT Review, 12th Edition

here are my thoughts about this book:

Strengths:
1. 907 real GMAT questions retired from past tests
2. Practice questions are organized by level of difficulty
3. Practice questions follow actual GMAT test patterns (it's great to have one's ear trained, esp. in verbal)
4. Contains a 100-question diagnostic test

Weaknesses:
1. Does not include any test-taking strategies
2. Though it has a few short review sections for each area, they are weak and very unfriendly
3. Questions are predominantly low to medium in difficulty which is often not representative of questions one encounters on the test
4. There is a 66% overlap with the previous version (11th edition)

Contents (number of questions per section):
1. Diagnostic Test - 100 questions
2. Problem Solving - 230 questions
3. Data Sufficiency - 174 questions
4. Reading Comprehension - 139 questions
5. Critical Reasoning - 124 questions
6. Sentence Correction - 140 questions

* Why is this book valuable/must-have?
The Official Guide is published by the creators of the GMAT and therefore it is the only source of actual GMAT questions representative of what you will see on the test.

* Why is the book not sufficient by itself?
This Guide contains only questions and lacks insightful information about the test, a math/verbal concept review section, or any test-taking strategies. To get up to speed, you will need to get a study guide such as Kaplan Premier Program or Princeton Review's Cracking the GMAT Cat.

* How should this book be used?
This book should NOT be used as a study-guide. It is a collection of questions - think of it as a way to practice your test-taking strategies but not a way to learn them.

* What if I own a previous edition of this book?
If you have the 11th edition, the only difference between the two is 300 new questions, or about 30%. Most test-takers agree that 300 new questions is not a compelling enough reason to own both editions, as the 11th edition offers enough practice. If you do need additional practice questions, get the Math or Verbal workbooks instead as they each have 300 questions.

* What is a recommended study plan using The Official Guide?
There are a number of approaches that work - here is one that most find reasonable:

Step 1: Buy a GMAT Guide from Kaplan or Princeton Review. Get familiar with the test and brush up on fundamentals (math and grammar); also these books will give you a good base for test-taking and timing strategies.

Step 2: Take a GMAT Prep (2 free tests downloadable from MBA.com) - but don't waste these; these are free but very valuable tests. Take 1 after you go through the Guidebooks and save the second one for later. These tests will be representative of your GMAT score (plus/minus 40 points).

Step 3: (Optional - if you want a 650+ score) Get a specialized Math and/or Verbal workbook from Kaplan, the 8-book set form Manhattan GMAT and do a deep dive into the fundamentals - this is what will help you crack the test - solid knowledge of Math and Grammar.

Step 4: By now you should have a good understanding of question patterns, strategies, and timing. Start working on the Official Guide and honing your skills - this is especially important for Critical Reasoning questions that have certain unspoken patterns and rules that only the Official Guide offers - work through the questions to train your ear. Keep in mind that these questions are on the easier side if you are aiming for 650+.