This is a great movie. I will suggest people watch it and decide for themselves instead of listening to other people's opinions.
I was pleasantly surprised because I'm not a fan of zombie movies but this one is really good.
I think the lesson to be gotten from it is survival. They didn't focus on trying to tell us what disease caused people to become zombies, they only tried to tell us what we can do if we ever find ourselves in such situation.
I applaud how they showed us that the leads almost gave up and didn't paint them as strong people.
They are just two people that gave strength to each other at a low point in their lives.