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 1999 (MRP) on the New Official Guide for GMAT 2019 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 real past GMAT questions contained in those books and the difference between the various editions of the official GMAT guides..
What the above analysis tells us that if you already have the OG 2018 edition, it does not make much sense purchasing the new official GMAT guide 2019 release.
If you have the 2017 edition, then you are looking at 655 overlapping and 252 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 OG 2019 guide.
If you have the 2016 edition, then you are looking at 517 overlapping and 390 new questions, Since there are close to 400 new questions, it would be worth purchasing the OG 2019 book.
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 editions, 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, and the trend has continued since. 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!