I've always been fascinated with the Red Wizards, and this book provides everything you need to create a campaign in Thay. It's full of lore, history, politics, and even little things I've never seen in other D&D books, like food (with recipes for you to try at home).
Even if you don't play in the Forgotten Realms, this is a great example of world-building. And the adventure included at the end of the book is quite entertaining, can't wait to play it.
[5 of 5 Stars!]