What are some of the literary questions that The Hound of the Baskervilles raises?

Q: How does the use of Watson as the narrator's voice aid the author in maintaining the tension of the plot?
A: Since Watson's powers of deduction and criminal analysis are no match for Holmes', placing him as the narrator allows the author to maintain the tension between the supernaturalist and scientific materialist explanations put forward by the various characters. That way, the resolution of the mystery is put off until the end of the story.
Q: How does The Hound of the Baskervilles both confirm and subvert the genre of the Gothic novel?
A: The author uses the conventional marvelous apparitions and settings (in this case, the hell hound, the 'castle', the ancestral curse, and the spooky moors), but he subverts the genre by revealing that no supernatural explanations of these elements are required.
Q: Compare and contrast The Hound of the Baskervilles with another Gothic novel. What elements are common to both, and how does Sir Arthur Conan Doyle's treatment differ?
A: In The Castle of Otranto, the supernatural elements (the giant floating helmet, the giant limbs, the groaning ancestor portraits, and the talking spectral skeleton monk) are all real. In The Hound of the Baskervilles, all of the apparently supernatural elements have perfectly rational explanations.