This book is good, but the main problem with it is that it does not give all of the criteria to get the grades. This is especially true with the mathematics units (6 and 8) which I have done so far. My class did all the criteria given in the book for those two units, and our examiner was the person who actually wrote those sections. He denied it, saying we didn't do any of the criteria properly, and we were forced to do those units completely over again in the two months we had left, on top of our other units; and we only had enough time to get the pass criteria for them. Not very happy at all.
But because it is the only book of its type on the market, it is a very useful resource for getting the majority of the information required for the mandatory units. It is a must-buy for anyone doing BTEC Applied Science Level 3, but users should definitely not use it as the prime resource, especially around the mathematics units.