I'm not really sure if I liked this one or not. The 2nd person didn't annoy me as much as usual, but it did still annoy me--I have yet to see a 2nd person story that wouldn't have been better in 1st or 3rd. I think this one definitely benefited from being read out loud. The beginning seems like it would be really boring to just read a list of condiments, but Ben did a good job reading it, well enough that I listened to the end.
I worked my share of service jobs in high school and college, mostly gas stations, but also at Target. I can definitely relate to the effect it has on you. I tried my best to be cheerful and personable, and some people noticed and returned the favor, but most just moved like robots, extending their money grabbing their change. The worst part is that after college, now that I'm working as engineer, if I don't think about it, I lapse into the robot-customer mode unless I remind myself what it was like to do that.
I've got to agree with wakela that with all the sandwich making detail, a little more detail about the rat poison death would've been good.
Overall, I thought the story was very good, it invoked real feelings, and the monotony of the beginning served as a surprisingly good hook--monotony not generally being great for drawing my attention. But the poisonings, including his own, were so blandly described that i didn't much care what happened to teh customer or to himself.