This book contains a large variety of songs ranging from the earliest songs of the Jackson 5 in the early 70s to more modern songs like You Rock my World and Dangerous from the 90s/early 2000s, which was when Jackson was in the prime of his career. I feel the book contains appropriate songs, most of his number one hits are included, as well as most of the songs in the Thriller albulm. From what I hear, a few songs that were essential from Michael like Earth Song or Never Say Goodbye were not included, but seeing as this book is based strictly on the 2005 CD of the same name, this is forgivable. Most songs are great but a few don't translate the best to keyboard, but like every book, there are always those few songs that make the entire book worth buying and the less desirable songs forgivable. As for difficulty, this book is not for beginner or early intermmediate players. There are a lot of sharps and flats in many of the songs, which are in the original key Jackson sang them in. They aren't really advanced either like Joplin or Gershwin, but they are on the more difficult side of moderate. One last comment is some of these songs for the piano part include a counter melody to the vocal part rather than go along with the melody, so for those songs you need to play off the top melody and add extra inversions to the notes to add more emphasis if you want to play the main melody, however, most of the songs' piano parts do go along with the main melody exactly note for note, but Bad and Thriller are some that don't. Overall, this book is pretty great and offers lyrics and chords, as well as great melodies and counter melodies for the vocals on piano. If you are a fan of Jackson and play piano, this book is a must have. If you like a few of Jackson's songs and are a pop fan, I still guaruntee you will like this book. It just has a really great variety and his best songs are all in here.