I got this book when I just learned to play the prelude 1 c major, and thought I would look into others later, even though the majority of those preludes and fugues are far beyond my ability to play. Since then I have tried to play prelude 2 (I) and prelude 24 (II) that is extremly beautiful though not easy to play, and I have listened all preludes and some fugues from CD or midi files with this book opened in front of me. I realized how great Bach's music is. Only complaint is that the cover of the book isn't glued strong enough, which is now seperated from the content pages already after only a short period use. Also, the prelude 1 (book I) is probably the correct version, but I have seen from some other books the other version with an extra measure between bar 22 and 23. I now play it with the extra measure since it seems making sense to me.