Perhaps the most well-known of Arthur Conan Doyle's Sherlock Holmes mysteries, The Hound of the Baskervilles was weaker than I expected. Doyle's fascination with the spiritual and the fantastical is clearly at work here; however, unlike in stories like A Study in Scarlet and The Valley of Fear where the spiritualism is dramatic and real, The Hound of the Baskervilles feels like an awkward fantasy/detective fan fiction. Sherlock Holmes is as dashing as ever, but the plot drags and the ending is all too evident (and overrated).
A Study in Scarlet is still the best Sherlock Holmes mystery, so I recommend you start with it. Move on to Baskervilles
if you're dying to see Holmes in action again.