This was the peak of Shan's formulaic plot lines. He starts slow, bringing the story and the theme to the forefront and then ends the books with a cliffhanger. This actually works for the series, however, because each of these books are novellette size, so you never get to the point where you cant go on. In the midst of this Shan gives you a (direct) moral, and he has more going on in this series than in any of the other series he has.
We finally get the back story of the main antagonists and Dr. Oystein, and we begin to understand the machinations that have been going on behind the scenes. We also have our first betrayal (though I have my doubts as to this characters motivations, and if he actually DID betray anyone), and we have a big reveal, which to me wasn't much of a surprise, BUT it will make for an interesting plot line for the next book.