I just read this over Christmas. I enjoyed it, but then again, anything of Koontz's would have been an improvement after The Taking.
Koontz was back in what I call "flippant mode" here, with a plot that was entertaining but certainly wasn't to be taken seriously. Would characters in the kind of situations they were in really wisecrack like they do here? After a while, it started to get too annoying, but I was still rooting for them.
I didn't like the twist near the end - I thought it was unnecessary, a kind of redundant device just shoe-horned in for the sake of shock tactics. The whole "plot" was bizarre to say the least! You have to wonder what Koontz had been taking before he wrote this one!
So: rubbish, but
entertaining rubbish. (Unlike The Taking, which was just rubbish.)