I just can't remember my reaction after reading the complete collection years ago, so the low score is coloured by lack of a strong memory, coupled with the really hilarious stories of Doyle -- who was a medical doctor by training -- and his gullibility when it came to the Victorian craze of following spirit-readings with ectoplasm-spewing mediums.
There is a story that Houdini -- whom Doyle broke with when Doyle's wife claimed to channel Houdini's mother without speaking the requisite Hungarian -- that Houdini was sitting in the back of a taxi with Doyle and played the "where's my thumb?" child's game to Doyle's utter amazement.