I found a Complete Sherlock Holmes in a Goodwill in Chicago and I've been chewing through it steadily ever since. I remember reading Doyle when I was twelve or 13 and really digging it, and it's every bit as good as I remember it. Not so much as mystery for mystery's sake -- there are much better practitioners of the art who've refined and perfected the form in the last 100 years. By comparison, the Holmes mysteries are pretty creaky stuff.
What I really like is the Victorian atmosphere, the specific details of 19th century London, and the unconsciously racist social attitudes. Not that I approve of racism, but it's fascinating how un-self-consciously it's presented. Since Doyle's goal is to use his surroundings and culture as backdrop for his ripping yarns, not to consciously comment on his society, it's likely as accurate portrait of middle class 19th Century London as can be had.
It's a little like what I used to do in the Driver's Ed simulators in high school. I was so fascinated by the 20-year old films of Florida streets, from which we were supposed to be learning driving skills, that I'd regularly miss turns and drive up curbs at pedestrians. The old cars, the signage, the way people on the streets were dressed was so beside the point of the movies, they captured the mundane details of the past in a way that no movie made to focus on them could.
But anyway, if you're casting about for something fun to read, you can do a lot worse than Doyle. The characters and settings are wonderful, and even if Watson's war wound migrates from his shoulder to the leg somewhere between the first two novels, he is an elegant, fluid prose stylist.