The major trend in this period was the Turks moving in, overwhelming the Arab Muslims and threatening the Byzantines.
The Turks adopted Islam, but they were Turks first and foremost, rather than Muslims. The religious angle was secondary to the ethnic.
Not to say the book isn't good, just that it may not reflect the most important factor (IMO!).
The Muslims WERE the story for quite some time. Never read this book, but sometimes reading from the other point of view helps you to understand the mind set. I would be interested in your thoughts on the book.