Like most of Curran's works, Nightcrawlers is big on atmosphere, detailed descriptions, Lovecraftian overtones, and gross-out horror. Unlike most of Curran's works, Nightcrawlers is extremely light on memorable characters or their any kind of decent development. Instead, the reader is tasked to deal with a group of almost interchangeable police officers, state troopers and other law enforcement officers. In fact, they're so alike that Curran at one point loses track of which character he is following, dropping in the wrong name mid-way through a chapter. Most of the officers are given one defining characteristic to remember them by, such as Chipney, who had a family at home. (And I bet you can guess what his chances of survival are ...)
What Curran does do well is flesh out his monsters, and Nightcrawlers is no exception. The things hiding beneath Bellac Fields and what drives them to do what they do are both unique and unsettling enough to be remembered. And it's this aspect that saves Nightcrawlers from being a disappointing failure, propping it up into being an okay way to spend 270-odd pages.
In essence, as far as this reader of horror is concerned, Nightcrawlers was a lesser entry into Curran's rapidly growing bibliography. He has far superior works - novels like Dead Sea and novellas such as Blackout - which should serve as better introductions to what he is capable of. But if you're already a Curran-fan looking for something without much investment which might cause you a shudder or two of revulsion, then this one should do the job. If only just adequately.
2.5 to 3 Bad Ways to Go for Nightcrawlers.