Ventajas
Flexibility of working for an independent supermarket, in the context of limited corporate overview. Part-time work with flexible hours, if that's what you're looking for. But it's minimum wage work, and you may have to get a couple of these part-time jobs to make ends meet!
Desventajas
Lack of long term strategic thinking. Lack of 'aspiration' leads to lack of inspiration. It's simply a 'McJob' for virtually everyone working in the stores. No internal program to train and promote from within. It's simply easier to hire someone from another grocery store and plug them in. Almost no full-time positions in the stores, which means no company-paid benefits (insurance).