Pros
There's plenty to do so you're never bored and everyone seems to get along pretty well. The pay is very good compared to other grocery stores and management will always let you try new jobs and tasks if you're bored and express an interest. Management is pretty even in how they treat baggers and managers. Benefits are good and even part timers can get medical coverage. You'll probably be in a union which has its ups and downs but definetly helps if management tries to fire you, and it also seems to help with the benefits packages they decide to offer.
Cons
You'll have to pay union dues and understanding your paycheck can get hairy as union contracts come into play, but its usually to your benefit. To become a full time hourly employee you're almost guaranteed to have to go through the Bake Shop to prove yourself (unless you're in Deli/Meat - different union) and there's usually a long waiting line of people who want to do it. You're going to have to deal with customers no matter where you are in the store and you'll meet some special people (like a man who will bring in the licked clean carcass of a rotisere chicken and ask for a refund since it didn't taste right). Getting time off can be sticky if you're sick even with a doctor's note.