From the little I have read of this (concerning the War of the Ring), it can be seen that this work details much of the history not included in the Silmarillion. That being said, it is of the same style, and many readers will find it hard to digest. However, this volume's purpose is to augment that set out in the previous work as well as the Lord of the Rings trilogy, so reading those books would, I believe, make for a more enjoyable experience.