On one of the Goodreads groups that discuss Sherlock Holmes, one topic is "pastiche" versus "fan fiction." The consensus - and my opinion - is that a pastiche tries to imitate Conan Doyle's writing style and to keep the characters and setting faithful to the canon. Sherlock Holmes & the Beast of the Stapletons is fan fiction.
First the good: the book itself is well produced with a striking cover and attractive layout. It would make a good gift for a Sherlock reader, provided the reader hadn't actually read the Hound of the Baskervilles. I also thought the way Holmes himself came off was pretty faithful and the writing wasn't bad, but it wasn't Doyle.
Now, the problems: The rambling and implausible plot takes place 5 years after the adventure of the hound, and Henry Baskerville is a widower who has become a near recluse since the death of his wife, who appeared to have fallen victim to a mysterious giant moth plaguing the moors. Holmes is consulted about the mystery by Grier, a black man and Masonic brother of Henry, who is referred to as a "Canadian by birth." Now in HOB, Henry is English and had lived with his father on the South Coast (of England) and only after his father's death did he go to America. Stapleton, at one point is referred to as "Jack Baskerville" - he was, of course, aka "Jack Stapleton" but never "Jack Baskerville". he was the son of Rodger Baskerville and Holmes learns that his real name is also Rodger. Henry makes a comment about selling Baskerville Hall, which he can't do since it's entailed, and there are references to his romancing a few women after HOB,, but in the text Henry's nerves are shattered and he goes off on a long sea voyage around the world with Mortimer. Doctor Mortimer is unaccountably portrayed as and referred to as a "bachelor" - but Mortimer is a married man in HOB, and there are no suggestions that he was ever widowed.
There are more such errors (only a long-time dog owner like myself might recognize the one involving a German Shepherd) that made me wonder where the editors were on this, and whether the author had even read The Hound of the Baskervilles. I do like Holmes tales that bring back characters from previous stories, but as interesting as the premise of a new curse of the Baskervilles might be, this one was just riddled with too many Canonical errors.