The book covers modules 1, 2, 3, 4 and 8 of the JAR EASA part 66 syllabus. The content is easy to read and understand however it is not the complete book if ypu are expecting to sit the full part EASA part 66 B1 course.
The book lacks extensive detail and is absent of material for modules 5, 6, 7, 10, 11, 12, 15 and 17. Also, when using the book I have encountered some incorrect answers, (the boom give examples for you to try with answers in the back, several of these answers are incorrect); I feel 1 or 2 errors are acceptable but just in the maths I have encounterd 4 and I have not used all of the chapter to complete the module exam.
However, it is probably the best book to buy if you are ot learn aircraft engineering