This book is extremely helpful, the way the author teaches the words is fantastic and reduces the chances of the reader forgetting the words. Also, one can understand the meanings of new words by seeing the root suffixes or prefixes or root words in that new word.
To get the best out of it, religiously do the exercises given and test yourself using the 3 test papers after the three sections respectively.
Useful to get into DU and for exams like Bank PO and UPSC.