This book tells half of the history of the Targaryens from Aegon the Conqueror to Aegon III. It's not written as a novel, but as a history book by one of the archmaesters of the Citadel in Oldtown. So it's very different from the novels of the main series, with no dialogues and characters' introspection. Nevertheless, it's a very interesting and entertaining reading, at least for a fan of the ASOIAF series. Sometimes all the names of lords, regents, kings and queens are a bit overwhelming and it's kind of challenging to remember who sides with whom and who's related to whom, in particular in the chapters about the Dance of the Dragons. For the Targaryens, the family tree at the end of the book was really helpful. Finally, the illustrations are very beautiful.