For myself, I'm a world lover or a History of Middle Earth lover. The Sil is my favorite book ever and I can't stop reading it. Every time I pick up another book to read I get board and re-read the Sil. The Sil establishes everything that the LotR is based on. All of the cities have a rich history and it's hard to appreciate the LotR until you know what Elves and Men had been through to get to that point. In order to appreciate Sauron's evil you have to meet his mentor, Melkor.
