This book is fantastic resource to prepare for an HSK exam. It is well-structured and thorough. I would recommend buying this book instead of plain mock tests as the analysis facilitates comprehension of what is required from a test taker.
It would be great if a similar and separate book on HSK Common Mistakes is written by the authors. Nevertheless, I believe that if I study for an HSK exam using this book, I will be more confident in Chinese and will pass the test as a bonus.
A big thank you to the authors, publisher, Purple Culture and all involved. Great resource for the good price. Delivery is still expensive, though :-)