I wish they had a chapter select or a couple of save slots. I guess the only redeeming factor about not having these things is that ALL of the accumulative achievements carry over across your multiple times playing the game.
And I like the game so I will still have to figure out where the last survivors are and have my car breakdown a few more times and I know there is another one but I cannot remember what it is lol.
Maybe the people who made the game knew that IF you really wanted to you could probably beat the game in a couple of hours anyways once you knew where all the zombies were and cutscenes to keep you out of trouble as well. So its not too big of a deal too make some of the achievements a little harder to get just to give you a reason to play it some more.