The Passage blew me away, I love the scope of time from the first quarter/half to the other. Very cool take on the Vampire/mutant, and throw in post-apocalyptic survival tastiness and you're in for a good time.
The Twelve was a little different for me, mainly because the novelty of the world and discovery of the world had worn off. We are already familiar and know what we are getting into here. The first book took me by surprise and enchanted me (even though it followed a pretty predictable, yet satisfying format). Some of the characters were less robust, and I was especially a bit disappointed by the action/plot event towards the end of the book. Thing felt rush and had that "wrapped up in a neat bow" feeling for the finale. I'll read the third and final when it comes out because I have to see how it all ends, since I am already invested in the universe.