I had been warned that there was a drop-down in quality for the second half of the short stories, and that indeed proved to be the case. His Last Bow holds up to a certain degree - "The Bruce-Partington Plans" was OK, I guess, and I liked "The Adventure of the Devil's Foot," simply for the scene of Watson rescuing Holmes from his own deadly obsessive intellectual curiosity, and "The Adventure of the Dying Detective," just for the ridiculously transparent "I'm dyyyyyying, Watson; don't you feel so horrrribly guilty for having abandoned me?!" drama from Holmes. (Doyle put some of his best effort in these volumes into cementing the friendship between Watson & Holmes, though the bit of over-obvious "not romantic no certainly not" spackling is slightly intrusive on occasion.)
Much of Case-Book is pretty thin, though. "Sussex Vampire" and "Blanched Soldier" were actually quite good, and parts of "Illustrious Client," despite the middling mystery, were actually pretty holy-hell, but "Three Gables" and "Shoscombe Old Place"'s racism and "Creeping Man"'s sheer ridiculousness deserve all the derision they receive, and most of the rest ("Veiled Lodger"; "Thor Bridge") is just meh. I see how Doyle is later on trying new perspectives to enliven a series of which he was supposedly tired of writing - having Holmes or a third party narrate a story; narrating Holmes' "last" adventure, a WWI intrigue, long after the rest of the narrative - but these tactics seldom add anything (for all his complaining about Watson's preference for thrills and sentiment over detailing the detective work, Holmes really doesn't write that much differently from Watson, for one).
Also, I hate little Billy.
Novels: The Hound of the Baskervilles is good and atmospheric, with a meaty role for Watson and Holmes at his least jerkish, but I was expecting more out of the mystery for some reason. It's solid but lacks the blindsides of the early short stories. That said, it's still the highlight of the collection and the best of the four novels.
I saved The Valley of Fear for last, having heard that it featured the return of Moriarty, and boy, was that a mistake. I was patient through the not-bad but still gears-spinning novella-long lead-up, only to get: "Hey, remember A Study in Scarlet and how it midway through took a right turn into Evil Mormons? WELL, GUESS WHAT?!" And no Moriarty was to be had. I guess Doyle was so intimidated by the prospect of writing Sherlock Holmes' supposed greatest challenge that he copped out all together.