Of all the "tales from middle earth" books this is by far my favourite. In the end the first and second ages are only that interesting to me. While the third age really captures my imagination and is the one where the most fascinating and fleshed out characters and stories take place. This book collects fascinating lore on the third age outside of the scope of the LotR and the Hobbit. The story of the Wizards, the Stones, Galadriel and so on. If you've read the LotR and the Hobbit I would recommend this book before the other books about the time before the Hobbit (i.e the Silmarillion etc).