Many GMAT candidates have already purchased, or have access to, previous versions of the Official Guide for GMAT Review (OG), and are wondering whether it is worth spending INR 1899 (MRP) on the New Official Guide for GMAT 2018 edition. To make it easier for you to make that decision, we have given below a comparison of the recent editions of the Official GMAT Guide in terms of the past real GMAT questions contained in those books.
What the above analysis tells us that if you already have the OG 2017 edition, it does not make sense purchasing the new 2018 release.
If you have the 2016 edition, then you are looking at 647 overlapping and 260 new questions. In which case, the money will be better spent purchasing some other Official GMAT Prep Material such as Exam Pack 1 and/or 2, rather than the 2018 guide.
On the other hand, if you do not have any GMAT Official Guide to refer to, or have the Official Guide for GMAT Review 2015 edition, then there is no doubt that you will have lots to gain by purchasing the new book. Also remember, the overall quality of questions in OG 2016 was a lot better than in 2015. So you are getting not only a substantial number of new questions, but also better quality questions. Over the last few editions of the OG, we are noticing a good improvement in Reading Comprehension questions and in the Medium to Medium-High range of Quantitative questions.
Best of luck for your GMAT Prep!