I read a lot of books in this genre. This book started out very promising, and the progression of the epidemic was fast paced and well described. I noticed several other reviewers made comments about how gory the descriptions were - well, that is to be expected in a book like this, and it didn't bother me at all.
However, some items were left hanging in the backstories of the characters. The author did a great job with their interactions with each other, but there were pieces of each character that were obviously driving them - the author even made allusions to them and did provide partial backstory for some, more here, less there - it was somewhat scattershot. Despite this, I'm still glad I read it.
I'd put this book in my "cotton candy" reading list - a good, fast read in a genre I like. The type of book to take with you down the shore or on a business trip where you need a book to while away the hours in a pleasant way.