Unlike most hard-core Stephen King fans, I have been reading his books in no particular order...just whichever one I can get my hands on next. Thus, I happened to read the entire Dark Tower series penned by King before I happened onto this novel. In that series, I learned more about Father Callahan, who was first introduced in this book. By reading things so disjointed, I figured that "Salem's Lot" was just a book about vampires who had to be expelled from a small town. Once I dove into this text, however, I realized that the true genius of this novel has nothing to do with the vampires themselves, but more so how King sets up their appearance.
The biggest thing that surprised me about this book was that actual vampires do not appear until the last 100 or so pages of the novel. They are hinted at many times earlier, but never fully exposed/explained. However, at least to me, that is where King makes this story so scary. Pretty much the entire first half of the book is devoted to trying to capture the small-town feel of Jerusalem's Lot but examining its citizens, their relationships, and the day-to-day events of the little town. Thus, when the great evil is unearthed towards the end of the novel, it makes it all the scarier that the evil is coming from such an out-of-the-way place, a type of place usually reserved for a slow, uncomplicated life. That, not the vampires, is the most interesting theme of the novel.
Of course, in typical King fashion, the characters are also very well-written and interesting, thus easy to root for (or against, in some cases) as they fight to extinguish the evil in small-town America.
So, although "Salem's Lot" was first published way back in 1975, it is still a thrilling read even today, as small-towns still exist all over America...small towns where he feel safe and never think anything can hurt is. In King's universe, that is not so, which is what makes this book so frightful.