I'm a huge fan of fantasy and post apocalyptic novels, but I have little experience with romance novels and no experience with Nora Roberts, so I have a hard time judging the book too harshly. I enjoyed the casual view of societal collapse due to a mystical virus that wipes out most of humanity in a matter of weeks. I wasn't expecting the brutality of a dark tome like King's 'The Stand', but it was surprisingly bloody. I also enjoyed a lot of subtle survival horror elements of Arlys's and Max's bands of survivors.
I didn't enjoy the random change in direction the plot takes around 4/5ths of the way in. It's as if the conjoining story that the author built towards was abandoned for a new plot. I also thought the villains were a bit shallow. Without spoiling, one group just ups and become villains with no real reason given. The other group congeals in a way that you could see coming, but the initial 'big baddies' just sort of take a hard turn towards villainy without an explanation. Strangely, the two villain groups hold diametrically opposing ideologies, yet they end up working together for a purpose that blends prophecy and petty revenge. All that said, I can't judge the book too harshly because of those minor foibles. Especially keeping in mind it's a mash between romance and fantasy with a bit of horror, but the book begins with a stronger than expected dose of horror that putters out 1/4th of the way in.
The last criticism I tried to ignore but has become increasingly difficult to shake off. The characters were woefully stereotypical and not very diverse. The heroes are a-typical alpha males who know it all and can do it all. The primary female character is a damsel in distress that constantly requires rescue or guidance from one of the alpha males. The very few characters of color seem sprinkled in purely for the purpose of slipping in a few jokes and filler. It feels harsh to criticize for things that only up until very recently were accepted standards in speculative fiction, but this was written recently. From a modern lens it's hard to ignore.
Overall: An OK read with a few flaws. I wouldn't recommend for those strictly reading for its fantasy or dystopia elements. If you are looking for light reading this might do, but it just wasn't for me.