Review The Official Guide for GMAT Review, 12th Edition
Description Review Compare 11th and 12th edition GMAT Preparation Guide Compare Price
Over time, even long periods of time, standardized tests don't change very much. The GMAT is no exception. Because the test is standardized, business schools must be able to compare test-takers today with test-takers up to five years ago. The exam can make subtle alterations but little else.
That fundamental consistency is reflected in the shift from the 11th edition to the 12th edition of The Official Guide for GMAT Review. Just as the 10th edition remains adequate (if not ideal) for GMAT preparation, there's very little in the 12th edition that the 11th edition doesn't provide.
The Official Guide is a necessary part of your GMAT preparation, as it contains hundreds of retired test questions. You can't get those through any other source, and they are the best way to familiarize yourself with the content and format of the GMAT.
The Official Guide is most valuable because of the realistic practice material. There are explanations for each question, though many students do not find those all that useful. There are also content overviews in the book, but again, they don't compare favorably to other sources. The value is in the test-like practice.
Compare The Official Guide for GMAT Review 11th and 12th edition
Description Review Compare 11th and 12th edition GMAT Preparation Guide Compare Price
What's Old, What's New
The overall format of the 12th edition is virtually identical to the previous one. The introductory chapters and diagnostic tests are the same, and the number of questions in each section is almost equal, as well.
Further, the 12th edition contains a lot of practice material that overlaps with the 11th edition, especially in the Problem Solving and Data Sufficiency sections. The overlap is at least half, and perhaps closer to 75%. Many of the questions in the 12th edition that are not in the 11th edition have been available in the GMATPrep practice tests or in the GMAT Focus diagnostics.
There is more new material in the Verbal chapters, especially in Reading Comprehension. I only recognized two RC passages from the 11th edition. There are plenty of new items in Critical Reasoning and Sentence Correction, but not nearly the same proportion as in RC.
The Same Old GMAT
There may be 300 or more practice questions in the 12th edition of The Official Guide that did not appear in the 11th edition, but that doesn't mean they represent a radical shift in test content. They don't.
Many of the new questions, especially in the Verbal sections, are different only in topic from older questions. A weaken question is a weaken question, and a fractions question is always more or less the same. The Critical Reasoning section does contain a handful of bold-face questions, which are not new, but did not appear in the 11th edition.
If there is any new trend, it's a slightly higher number of functions, symbolism, and sequences problems. That's part of the GMAT's steady, if slow, shift to more abstract content. While those questions are worth paying attention to, don't overreact. The "new" topics will probably not represent more than one or two questions on your GMAT.
Should You Buy the 12th Edition?
If you've been studying for the GMAT with the 11th edition of The Official Guide for a long time and your test is coming up, there's not much point in switching over to the new book. The 11th edition does a fine job of preparing you for what you'll see on the test right now.
On the other hand, if you have the 11th edition but haven't really started using it, it's worth the additional investment to move to the 12th edition. The difference is slight, but the 12th edition practice questions probably do correlate a little better to what you'll see on test day.
Whatever you do, pick one book and stick with it. As I've said, there's a lot of overlap between the two books, and even in the non-overlapping material, there isn't much difference. It isn't worth your time, effort, or stress to try to eke every last edge out both editions. That kind of energy is best reserved for mastering test content.