I bought this book to give my piano technique a tune up and I've noticed overall that my playing is smoother and clearer. I would recommend a book like this over Czerny since there's no halfhearted attempt to make these exercises a piece of music and you just get straight to the finger calisthenics. Most of the "pieces" (usually just a measure or two) have to be transposed to all 12 keys, which exercises not just fingers, but also the ear and brain. I wouldn't call the exercises fun or easy, but going through them daily has benefited me and has made some of my difficulties with my regular rep disappear.