Mike Harnish has written an in-depth review of Trail of Cthulhu for wired.com. It provides a detailed break down of the contents and feel of the book.
By now it should be evident that I am a huge fan of Trail of Cthulhu. I think it manages to capture the feel Lovecraft’s stories, particularly when played in Purist mode, with rules built to complement the stories. GUMSHOE is a perfect fit for investigating the supernatural mysteries and horrors associated with the Cthulhu Mythos. It also is simple enough to be run in a more “off-the-cuff” improvisational style and doesn’t require a great deal of prep on the part of the GM, an important consideration for those of use with busy lives.