The PPL Confuser is a useful guide to the questions you'll get on the exams. However, as people have said it's too easy to learn the answers without fully understanding the subject. Its really up to you to use the book as an aid rather than using it as a script for the exams. Also worth mentioning is that most confusers still have 3 answers for each question where as the exams now have 4. They may have now updated the book however.
WD