I thoroughly enjoyed this novella, but I don't recommend it to anyone who hasn't already read at least Feed.
This is a prequel, giving little flashes of the days leading up to and immediately after the original Rising (or Zombie Apocalypse) in the world from the trilogy. It fleshes out a lot of the details that fans of the series have picked up, bit by bit, and gives more background.
However, I don't think it stands on its own as a story. But for a fan of the Newsflesh trilogy, it's definitely worth the price.