State of Decay is an awesome game and definitely worth the money! While far from perfect, it comes really close to the zombie survival simulation i've been waiting for. It's also nice to see that the developers have already submitted a title update to M$ to address some of the game's issues.
If you've been reading up on this game, don't get too discouraged by the complaints about frame rate/screen tearing -- it's really not as bad as some people make it out to be. The fun you'll have will outweigh these inconveniences.