Honestly, I'd buy this at £20, so at £2.75 it's a great deal. While CGP's general GCSE Maths Revision Guide is good, and there are CDs like "Maths Watch", nothing really comes close to this revision guide - it explains things clearly (including topics like stratified sampling, which isn't actually explained in the normal revision guides), is laid out well, has exam practice questions every few pages and even has two past papers at the back; it really is all that you need for the course.
I don't really like Maths, and I'm counting down the days until I can drop it, but this book makes the course quite easy and, whether you're a C or an A* grade student, you should really get this book.
I'm currently in year 11, and find this book to be pretty damn amazing! Didn't have the best teachers in year 9,10 and so had to self teach my self topics. This books brilliant for self teaching, and contains all Maths topics from Year 8 > Year 11.