"Viking Pirates and Christian Princes", (VPCP), is a very detailed and specific book that focuses on one geographical area through a particular period of time. This is definitely not a general introduction to Viking history overall, but rather a look at one manifestation of that history in the seas between Ireland and Scotland, Wales and the Isles therein.
Focusing on the Haraldson family and the descendents of Olaf Cuaran, the book attemmpts to show that the Vikings had a much wider impact on the surrounding peoples than just raiding and plundering. By following two powerful families and their political machinations over the region, the author does a good job of demonstrating his point.
The book is very detailed and there are many, many names to get one's head around. The fact that many people in the same families had the same names does not help, so frequent glances at the family trees may help with this. The two families chosen were major players in the Irish Sea region and made significant contributions to the political landscape of the area, even as far as York in England itself.
VPCP is a book about politics and its instruments, so the majority of the text is taken up with alliances, marriages and wars. However, it also delves into the motivations of the people concerned and what their thinking was, as far as that can be established. There are also aspects of social history dealt with too.
What one ends up with is a very detailed looked into the lives of specific Viking descendants who are trying to establish their own colonies and nations within the lands of larger native populations. It is a very interesting story and the history makes for fascinating reading.
As already mentioned, this is not a general history of wider Viking activities, but restricts itself to Scotland, Wales, Ireland England and the Kingdom of the Isles in scope. If something a little more specific is what one is after, then this would be a good book to acquire. For more general looks at Viking history, other books would be better suited, such as Viking Empires.