A cyborg from the future schoolgirl beats the crap out of zombies the way that puts T-1000 to shame. The whole idea is ridiculous; it would be equally ridiculous with a schoolboy being the main hero. I would have believe it if said schoolgirl had been raised by a martial art master training from the age of 5 of younger; but as it is a soldier just showed her how to fight - he must be a very talented sensei.
The whole book is just one zombie battle after another with a little - if any - time for character development. The core group keeps surviving while the rest of the people play the role or "redshirts" from Star Trek: promptly getting killed or infected by zombies. The sacrifice at the end and ensuring cliffhanger are the only redeeming features of the book.