The Silmarillion is the epitome of all of Tolkien's virtues. As a Tolkien book it's linguistic sophistication is virtually unmatched and I am personally an enthusiastic lover of his writing style. Its pre-eminent merit though is the world it creates and represents, this book expands the world to an unprecedented degree, fully fleshing out the history and culture of the nations of middle earth. Ultimately, it is up to you to discern your favoured book types, but I am a vehement advocate for this book to all and sundry.