Pros
It's a good company with a lot of locations. The people are nice and the pay is good once you get above entry level positions. There are many chances to advance within the company. Hours vary if you are part time but managment is very flexable. You can always request time off and your requests are almost always granted. King Soopers is a senority based employer which means that preferential tasks always go to the people who have worked there longer. For example if you are a courtesy clerk, you often end up checking (which means higher pay). The courtesy clerks who have been at the store longer get put into a checkstand before other employees.
Cons
There are a lot of customers from all walks of life. With so many people comming through every store there are bound to be some people that are difficult at best to work with or help. You're hours may vary greatly depending on the time of year. For example, you will work a lot of hours around Thanksgiving and Christmas, but in January you're hours will be cut a lot. If you are going to be part time, you pretty much have to work nights and weekends because the day shifts monday through friday are covered by full-time people. The work is pretty repetative, but very easy.