Bottom line up front. Incomplete. No real understanding of the religions portrayed.
This book falls into some of the pitfalls that other independent Savage Worlds setting books tend to do. Namely making changes for changes sake. There is a great deal of flexibility already built into the system. The Fantasy Companion and the Horror Companion add more for this genre. The author has added rules for armor (layering, arcane user penalties) that are cumbersome and unnecessary and have been addressed by mechanics in the core rules. Weapons are also treated with new cumbersome rules (basic and martial a la DnD, and up to +5 to hit!) that show a lack of understanding of the basic system. This could all be ignored, except then there wouldn't be much to use.
As a setting this book it is very incomplete. As mentioned by another reviewer. Western Europe is entirely left out of possible nations to use. So is Islam and the Arab conquests. Muslims had conquered Arabia, North Africa, Spain and had even marched on Paris by this time! They aren't in the setting. There is no explanation in the book why this is. As a Sandbox style setting this would be an epic fail.
The Plot Point campaign and Savage Tales exist which is a plus, however there are no Adventure generators and the Savage Tales are pretty sparse on details.
Religion is oversimplified to the point of dangerous. The Author tells us that religion plays a large part of the lives dark age peoples. It did but what we get in the book is grossly simplistic and wrong. The Plot Point campaign is set in Kievan Rus. There is no mention of the Eastern Orthodox Church (key to the formation of Kievan Rus) and its differences with the Roman Catholic Church. Although the Catholic Church is mentioned. The Catholic Church is represented as a inquisition driven organization with no mention of its powerful and altruistic unification of European culture. When specifics of Christian religion are mentioned it becomes a mish-mash of pantheistic theology poorly reminiscent of DnD. Christians are viewed as a bunch of haters whose main mortal sin is not punishing the wicked (which in this setting is everyone other than Christians). Reading between the lines the Christian Religion and its followers run a close second to the Demons as villains. In discussing Demons and the Undead the author cavalierly attributes motivations that are at odds with a functional alliance that stretches credulity from a secular standpoint let alone a theological one. And fails to logically explain why.
This setting book has tremendous potential. If you decide to buy it be ready for a lot of effort to make it work. I would suggest waiting for a re-write or another setting book.