I remember when I was young, and my grandfather gave me his paperback copy of W.S. Baring-Gould's biography of Sherlock Holmes, Sherlock Holmes of Baker Street. It was the first time I realized that there were Holmes fans who played what has come to be known as "the Great Game" (or the Sherlockian Game, or the Holmesian Game, or simpy the Game), wherein Sherlock Holmes and Dr. Watson and the rest are treated as historical figures, and Arthur Conan Doyle is cast in the role of Watson's "literary agent." Playing the Game, fans attempt to reconcile ACD's numerous errors and gaps in continuity (e.g., Watson having received a bullet wound in his shoulder...or is it his leg?). It's a tremendous amount of fun to approach the stories in this manner, and Baring-Gould's Holmes bio and his monumental Annotated Sherlock Holmes, as well as Leslie Klinger's New Annotated Sherlock Holmes, are perfect examples of how detailed the Game can get.
Some fans who enjoy playing the Great Game are probably a bit disappointed by the Oxford Sherlock Holmes, as the introductions and notes in that series treat the canon as the fictional series they are in what is usually known as "the real world." However, I for one am glad that the Oxford collection exists, because the publication history of the Sherlock Holmes stories and novels is fascinating in and of itself, and the Oxford series treats the works as worthwhile literature, which they certainly are. How fortunate we are to have such amazing resources, by those who play the Great Game, and by those who refuse to play it. Meanwhile, I always get a chuckle out of the little "disclaimer" immediately before the first chapter of Baring-Gould's Sherlock Holmes of Baker Street:
"No characters in this book are fictional, although the author should very much like to meet any who claim to be."
I'm a stay-at-home dad, and Director of Music Ministries at a United Methodist Church in Mt. Juliet, TN. And a longtime fan of Sherlock Holmes.