Pros
The benefits are some of the best, especially for part-time employees. Their ESOP program is industry leading and if you're willing to make WinCo your career, you'll retire very comfortably. One great thing is that it's a great entry level position that will give you many different and useful skills in the workforce. Additionally, depending on your department, the managers will work with your schedule. Personally, I worked 3 days a week while I was going to school. There is opportunity for growth if you want it, typically it's pretty easy to move up into the MIT or MA positions but you have to be willing to relocate.
Cons
The biggest con about working for WinCo is the salary. You will start at just above minimum wage and increases are based on hours worked. So if you are a student and can only work 20 hours a week, it will take you a very long time to move up in your steps. If you can consistently work 40 hours (and you get scheduled 40 hours) it typically translates to 1 raise per year. Another con about the company is there is a lot of turnover and you will quickly find yourself having the longest tenure and be in charge of training new hires.