This isn't going to be a proper review, because I find it hard to write reviews once you get more than an handful of books into a long running series.
This one is #21.
I will say that the storyline in this one creeped me out big time. What was truly going on beneath the surface was truly horrific. And for a series that hasn't shied away from the horrors humans can inflict on one another, that's really saying something.
Ohhhhh, but was it ever so good.