After I downloaded this for free via Bookbub, I perused a few pages to get a feel for it. Then (as per the norm) I hit up the Amazon reviews to see where it fell for the average reader. The ratings were so-so, so I didn't get my hopes up, but I liked the straightforward prose style and basic premise, so I kept reading.
I'm glad that I did. I zipped through this book and enjoyed it very much. While I initially expected a zombie apocalypse, what I got was far creepier and more intriguing. The questions I had about what was going on kept me reading to the end, and I felt 95% satisfied by the answers to those questions. Also, as another reviewer noted, Mr Powell's simple prose style gave just enough to paint the picture and tell the story with nothing extraneous. Other readers may prefer more pontificating, but I personally enjoy this style--it seems to remove the sometimes obtrusive writer from the story, if that makes sense.
Some of the negative reviews on Amazon commented that this was insulting and offensive to Mormonism. I am not a Mormon, but I still disagree with that characterization. Mr Powell has engaged in a 'what if' experiment, which is something that speculative fiction by definition does. The creation of this experiment in a fictional story does not necessarily reflect on an author's views--I suspect Mr Powell, while a self-professed atheist--finds most or all religions fascinating (based on his commentary in the epilogue). He did nothing here other than let his 'what if' experiment run out to the natural conclusions that he envisioned.
The ending and much of the plot was a little deus ex machina, but it didn't detract from the story for me. Or not much, anyway. Some scenes weren't as tense as they should have been, I think, but the novel worked well nonetheless.
And Mr Powell, if you're reading this, you should check out my book, "Loki: Nine Naughty Tales of the Trickster". I think it might be up your alley.
Mike Vasich