This was my first AD&D book. I bought this book for the sole information on dragons, but lo-and-behold when I read it further, I got information I never expected. If you're looking for the fifteen kinds of dragons located on the remote land of Io's Blood Island Chain and a good campaign option based on dragons and their kindred, this is your book. I found some things that could help me in my writings like the Great Wyrm info, the body lengths of the dragons, and the extended text on the the Metallic, Gem, and Chromatic dragons. This book explains everything you need to know about Io's dragons, from hoard treasure to proficiencies to Dragonic combat to dragon kits. It includes character sheets, marvelous illustrations, size charts and three adventures for the players.
The Council of Wyrms made me believe that AD&D wasn't just some game, and that I should look into it a little more.