To begin with, Faye obviously researched the hell out of this book. Her grasp on the Ripper killings was thorough and her familiarity with Victorian London, from Whitehall to Whitechapel, was complete. From the ease with which she made use of Victorian working class slang to the quality of the noxious London fogs, Faye knew her stuff. But best of all, she obviously knew Holmes. This is the only time I've read a non-canon Holmes and forgotten that Arthur Conan Doyle hadn't written it. Every choice in diction and syntax, every bit of characterization, both major and minor, were spot on imitations of Dr. John Watson's biographical "tone." There wasn't a false note in the thing, and believe me, I was looking for one.
Better still, Lindsey Faye posits a solution to the Ripper killings that not only explains who the killer was and how he managed to avoid capture, but why the identity of the killer was never revealed, if indeed it was ever known. The solution fits very neatly into the logic of Holmes's world, making it seem that it could never have happened any other way. Of course the fictional Sherlock Holmes successfully investigated the real life Ripper killings - why shouldn't he have?
All in all, I tore through Dust and Shadow. At first it was simply because I was kind of shocked by how good it was, but very quickly, the mystery pulled me in, as any good mystery should, and I ended up gobbling up page after page just for the pleasure of finding out who-done-it (the answer, let me tell you, is perfectly logical, but oddly chilling - something I was also not expecting). I can't recommend Dust and Shadow enough. If you like Sherlock Holmes, or Jack the Ripper or Victorian suspense, definitely pick it up. It really is a treat.