One aspect of this book which differs from similar stories was the premise that a hostile foreign power could manipulate right-wing, nationalist, paramilitary elements within the United States and utilize them as pawns to undermine our security and sovereignty. I have to say that this was an interesting and appealing departure from the main vein of this sub-genre, breaking from the pseudo-patriotic, ultra-conservative, war-mongering mindset commonly found in these types of post-apocalyptic tales.
On the other hand, this story had a couple major drawbacks. Firstly, the details on the military operations of the hostile foreign power - both at the tactical and strategic level - are something less than minimal. This is really more of a novella, so if you're looking for a sweeping, in-depth military thriller in the style of Tom Clancy, this will disappoint you.
Secondly, this story is guilty of conforming to a mentality which writer Rebecca Solnit calls "elite panic," and doesn't do NYC any favors in its portrayal of that city in a time of crisis. While a myriad of books, movies, and TV shows perpetuate the idea that disasters will lead to anarchy, social collapse, and a "dog-eat-dog" world, we find the opposite is true in numerous historical examples - including several from New York like 9/11 and Hurricane Sandy - and that most people in a time of upheaval actually band together, pool their resources, demonstrate acts of bravery and selflessness for even complete strangers, and form meaningful new bonds across social divisions. For more on this, check out the inspiring and iconoclast "A Paradise built in Hell" by Rebecca Solnit.