Let me just say that I love John Scalzi's writing. I've been a big fan of his since he released Old Man's War and I've continued to following along with The Ghost Brigades
and The Last Colony. That's why I picked up Zoe's Tale as this book takes place in the same universe and during the same time frame as The Last Colony. Except it is told from Zoe's point of view. To me the shared timeline is the books biggest fault. For those of us who've already read The Last Colony there is no sense of tension as we are already aware of the outcome of the conflicts within the book. This is the same problem I had with Ender's Shadow the companion novel to Ender's Game.
That is not to say that it isn't excellently written because it is. Scalzi does and great job of writing this young adult novel and he gives the teenager, Zoe, a believable voice. You'd almost think he has a teen or pre-teen stalking around his house ;)
I recommend this book to people who want to get into Scalzi's writing of the Old Mans War universe without having to invest in three books worth of material.