Oh Holmes was my constant companion when I was a teenager. Loved his analysis of every situation, and the boundless energy alternating with long periods of lethargy. Greatest detective ever !
In the first Holmes novel, Study in Scarlet, Watson makes up this list of Holmes's abilities and weaknesses in an attempt to discover his profession, for a long time I used to do that for everyone around me and try to figure if you can really tell a persons profession from his knowledge base. Turns out to be pretty difficult actually. And I never could do that trick of glancing at a guy and immediately giving a true description of his life and characteristics. But thats what made Holmes so much fun.
Loved his relation with Moriarty too, they were the good and bad side of the same coin. Watson has to be the most successful sidekick in the history of the genre, a simple foil to Holmes without being stupid and interesting in his own right.
About Conan Doyle's other work, I only remember Lost World, which was pretty impressive in the adventure genre, long before Jurassic Park and such movies. He wrote other stuff also, including poetry, I think, but never read it.
I did read once that he was extremely interested in miscarriages of justice, and at least twice paid for appeals for people who he thought were wrongly convicted (both were later exonerated, one of them was half-Indian). Any one know any more about that?