As a general GCSE history help guide this book is no better than OK. However, it is certainly not a 'Complete Revision'. Whilst I'd agree it would help lower level students as it sets out information in an easy to understand, simplistic format, I don't feel it covers the various topics with sufficient detail to accommodate the higher level student.
For example the suggested answers given in order to attain level 4, in my opinion, are not of adequate depth. If I was marking these answers they would not be acceptable to reach the highest level.
By all means use this book as a guide but students will need to fill in the many gaps from other resource material.