I've been meaning to read this book for years, and I only just got to it this year. Once I started reading it, I finished it in just a couple days. (First book of the year!...Don't worry, I finished it forever ago. I'm just behind on reviews.)
I think it would be hard for anyone to dislike this book (despite the weird Mormon stuff--which I'll get to in a minute). Like most people, I've seen adaptations of Sherlock Holmes and loved them. The original book did not disappoint. Holmes himself was just as awkward, egotistical, brilliant, condescending, and all-around fantastic as a character as every adaptation had made him out to be.
Now that I've seen the original character, I really love the way he lends himself to interpretation. Robert Downey, Jr. and Benedict Cumberbatch play Holmes in two distinct ways, and neither of these is the "original Holmes"--but each of them is right. There really is no "one Holmes" that everyone is trying to imitate. Sherlock Holmes is a character that can be taken in many different directions, and that's what I loved about him.
After taking a Victorian literature class that focused on short fiction, I thought this Sherlock Holmes story was a great example of Victorian short fiction (albeit a little long). Lighthearted and intriguing, it's completely fun, but it has some thought-provoking themes, as well. It never pretends to be Shakespeare, but it's great in its own way.
Now for a quick note on the Mormon weirdness...
Is it weird that I had NO idea this part was coming? I guess I haven't really seen that many adaptations of Sherlock Holmes, but I'd never even heard of this entire section of the book. I guess screenwriters and directors try to avoid it. I would, too. (I should probably mention that I'm actually a Mormon, myself, so the "weirdness" I'm talking about is not the fact that Mormons appeared in the book, but that they were described as such a creepy, cultish group.) Anyway, I have to admit the fictionalized portrayal of the early Mormons was pretty funny, what with all the secret murders and whatnot. I assume that Doyle's version of Mormonism was based on the popular prejudices of the time. Just hope everyone who reads the book today realizes that Doyle's portrayal of Mormons was largely fictionalized. :)