I read this book (actually, listened to an audio recording) 4-5 years ago. The post below contains my thoughts at the time.
This is another of those classics that I've been aware of for as long as I can remember, but had never actually read. Thanks to David Barnes at LibriVox, I listened to a recording of it yesterday and really liked it. It was one of those books where I knew the ending, but the journey was fascinating. Some people might call Stevenson verbose (he used quite a few words to describe rather simple things), but I loved the language. It's not a very long story, and probably could have been told in even fewer words, but I liked all the "ten cent" words that were thrown in. I found that I could really picture the characters and scenes and I like that. Of course, as a scientist, I thought the entire premise was bunk, but that didn't stop me from thinking about the duality of man and some of the other issues raised. In short, I recommend this and if you read it, you'll completely understand why Jekyll/Hyde has become synonymous with split personalities.