I ended up really enjoying this, although it could have been pared down significantly. McCammon's pace was a bit leisurely even for me, and I enjoy a slow-paced tale.
Overall, though, I liked Matthew Corbett and thought that the historical aspects were very well done. Colonial America is not one of my areas of interest, so I'm not even an "amateur expert," but it rang very true to me and I liked the setting. There was an abundance of gore, bodily effluent, rats, leeches and other unpleasant elements that historical fiction often glosses over.
This isn't really a supernatural story, and, although it would work for Spellbound with the witchcraft plot points, I've actually decided to use it for Creepy Crawlies, based on the prevalence of critters that scuttle, slither, bite and scratch that were part of the story.
I am really intrigued by the next book in the series, Queen of Bedlam, which has even better reviews than Speaks the Nightbird, although I'm not sure that I will get to it during Halloween Bingo. I'm vaguely planning on reading it for one of the squares that is not on my card (Serial/Spree killer, Modern Masters of Horror, or American Horror Story), so I won't start reading until I've blacked out my actual card.