Rating: WARTY!
This was Blatty's attempt to get back some of his former glory after The Exorcist supernova had faded. I thought that original offering was a great novel and I really enjoyed it, but this one, which I read some time ago yet did not realize until today that I hadn't reviewed it, was a poor, poor sequel.
Often when a writer has a huge hit it's hard for them to get anywhere near that point again. We've seen it with runaway best-seller writers like JK Rowling after the Harry Potter marathon, and Suzanne Collins after The Hunger Games and its sequels. Inevitably they're drawn back to retread old tires because efforts to go in other directions are met with indifference. Typically retracing steps is a mistake and it fails.
The plot for this is very confused, resurrecting people who clearly died in the original novel and turning the demon into a limp and unoriginal serial killer, jumping from living body to body to leave trademark serial killer crimes scenes but with different fingerprints. The book was clearly very badly-written, very confused, and not worth the reading. A better take on this idea is the Denzel Washington movie Fallen which did not perform well at the box office but which I think far outstrips both this novel and the movie that was made from it. I can't commend this particular novel as a worthy read.