Game of Thrones is one week away but the actual book's ETA is unknown. However, I stumbled on this book and thought it would be interesting until the Winds of Winter gets written and published. I honestly thought it would just be another history book explaining the backstory of the houses and more Westeros lore like you get in hidden in the back of the current novels but it turned out to be so much more.
It's written in the same GRRM style that made all the game of thrones book popular, and fills in so many gaps concerning the old Targaryen maester on the wall. When he was dying with Sam on the boat, he become demented and started screaming for his younger brother "Egg". (Short for Aegon Targaryen).
It was literally just a handful of lines in the GOT books and didn't think that this Egg character was important but again GRRM humbled me, writing a entire universe around those few lines. This book is about Egg, and set in place the chain of events that were to follow in the series.
I didn't get time to read it physically so I got the audible version to listen to when I was doing the dishes etc but what started out as curiosity ended in perfection.
If you want a good Game of Thrones fix before the final books, this is as authentic and satisfying as it gets. Definitely recommended.