I have probably been to over a half dozen different Potbelly's.
I love the toasted sandwiches, the fact you can get a "skinny" one with less bread, and I always get a root beer which looks like a regular beer if I bring it back to the office. And of course you have to get the peppers on your sandwich - but not too much or your stomach will make you pay.
But there is something that stands out about this particular Potbelly's. The staff have always been exceedingly nice! Most are always smiling and conversing without sacrificing any efficiency in getting you your food. I would be curious what the company culture and compensation is, or maybe this one just has a good manager.
In any case, it's one of my staples for lunch (5 min walk) whether I am eating in or taking out.