Pros
In short, I was able to become a shift manager in less than a month. This was largely because, unlike some of the people who had been working there for months (and in one case, over a year) I learned the menu.
Cons
They appear to have a standard of hiring the worst possible people for the job (or really any job). Although I know some people at other stores that are quality employees and have a decent staff, my store was filled with people who didn't know the menu, were unhygienic, has little or no customer service skills, and had to be continually monitored (or they'd do something bafflingly wrong). As I mentioned before, at my store there were employees who worked there for well over a year and did not know how to make a sandwich, wash dishes, or do basic tasks. Whether you're a driver or an in-shop, there are less than 20 menu items (and it's not like any of them have special preparation). Eventually I made a case for them to get shown the door but it was only after nearly six months of asking what certain employees had done to continue to work there. I was also only paid $8/hr to be a shift manager and made significantly more as a driver, so there was no real motivation for advancement. There were also points where I worked 28 days in a row (that's why it got one star for "work/life balance." I don't know whether it's like that at every JJ's.