Or as my family calls it the Cyberman book!!
Anyway it's very good, if off my current painting and gaming areas (must resist). It's a big canvas covering the Late Roman (i.e. Byzantine), Sassanid and Arab empires and touches on a lot. Much of the book is about the development of the key religions during late antiquity and the interactions between religion and state politics.
A topic that I found interesting was the fate of some of the lesser known sects and religions that lost out in the politics. I had encountered Manichaeism and Nestorian Christians in earlier readings about the Silk road, and it was interesting to find out where they came from before they self-exiled themselves to Central Asia.
So far I'm half way through and still haven't hit the conquests of Belisarius, Heraclius or Muhammad and his followers.