This text is a bare bones, just-the-facts overview of the world of wine as needed for the WSET Level 2 course, which means that it is very sparse on details in many areas and completely skips over anything not part of the curriculum. While it does provide an overview of the most important things in wine, it has been cut down a bit too harshly to fit the curriculum and so it only barely gives the appropriate context for a lot of the information it actually contains. Also the writing is very terse and dry, so don't expect it to be a page turner.
In regards to things that are missing it for instance mentions most important wine areas, and then has some detail on important appelations within some of the areas, but doesn't provide context to understand if those mentioned are the only relevant appelations in that area or just some out of many. Also the book is mainly organized around grape varieties, which by itself is good but it means the descriptions of growing areas and countries are rather messy and it doesn't even contain any maps for them, those are only in the study guide and then without descriptions which makes those details a bit hard to follow.
As a study book for the WSET2 course it works, barely, but just because it contains only the curriculum and nothing more. In regards to getting an in depth introduction to wine it left me with as many questions as it gave me answers. For actually learning about wine the WSET3 book is a lot better written and more complete, including being geographically organized by region and including maps. Unless you are taking the WSET2 course you should really pick another book.