You can pretty much sum up this book by calling it Martin’s version of The Silmarillion and the Lord of the Rings appendices rolled into one. Beautiful colour pictures bring the story to life, however, this is also its downside as those colour pictures and maps disappear in the last 3rd of the book. Meaning this part of the book offers nothing a search on Wikipedia would find. Because of the books price, this is its biggest downside.
From the beginning of the colonisation of Westeros by the first men right up until the start of the book series, this book covers everything. While it in no way fills the void that is 8 years without a new book in the series, it does with the help of some beautiful artwork try and ease our pain from our absence for so long from this fantastic world.