Fire and blood is a great book

I really enjoyed Fire and Blood, especially the Jaehaerys chapters. I thought it was a very detailed description of Targaryen history. I wish there were more chapters about the Doom of Valyria, and the Century of Blood. I don’t think George wants to give us all of the details of pre-doom Valyria because it will remove the mystery, which I personally think is the most interesting part of ASOIF. I could not put Fire and Blood down regardless. It sort of itched a scratch for me about pre GoT lore. Why do people not like this book? Besides the historical perspective.