The rationale behind BJ's originally was "soul food made healthier but just as tasty." So, for example, smoked turkey leg was used as a substitute for salt pork or ham hock.
We used to go to the Stony Island shop fairly regularly, but stopped after a really awful string of bad performances--the kitchen out of everything, the employees completely clueless about their jobs, the bathrooms in unspeakably bad shape, some unpleasant interactions with less-than-upstanding people hanging out in the lobby. I think all of this boiled down to a complete lack of management oversight. The 79th street shop is newer, so maybe management is paying attention to that place. If someone has a recent good experience to relate about BJ's, I'd love to know.
In all honesty, unless you have some health-related diet restrictions, I would go with some of the other great options on the South Side like Soul Queen, Army & Lou's, Yassa, Pearl's Place, Soul Vegetarian East, Uncle John's, Lem's, etc.