This isn't a masterpiece by any means, but it succeeds where a lot of survival/post-apocalypse stories fail. It's split into three parts which allow the characters to succeed, escape, find some sense of normalcy to their lives, and then escalate the stakes of the narrative later. This avoids the treadmill effect you have in The Walking Dead and other series which just devolve into 'oh they escaped some zombies, can't wait until next week when they run into some more zombies they need to escape from.'