Just finished watching seasons 1-3. First season was great. Second season was meh. Third season picked up a little, but the series just seems to be running out of plot. Where does this series go? The zombies are more of a nuisance than a threat, and continuing to defend the prison against bad guys is getting old. And as interesting as rebuilding society and subsistence farming in a zombie apocalypse might be in real life, it's going to make for really boring TV without more genuine conflict and exploration.
The show needs a change of scenery and, better yet, a quest. I'm hoping the prison gets overrun in the first episode, and they humans have to move on.