Pros
If you have the desire and the determination you can go far. Department heads are chosen by interviews, not seniority. Once you have become a dept head and prove your worth you can go into the management training program to create a career that pays better than a dept head could ever achieve. Since they are union, you don't have to worry about @ss kissing getting someone ahead who doesn't deserve to be there. I have dealt with great managers and awful managers. Luckily, the terrible ones usually get weeded out over a period of time and I consider this a good point.
Cons
As a regular clerk, you are relegated by seniority since they are union. You must work all holidays and most weekends and for most people that is a negative. Raises are not given based on your work ethic or production, they are given on a time line because they are union. Although dept heads make decent money ($16-17/hr) for what they do, there's no going up from there unless you go through Kroger's management program.