Pros
While I personally didn't find the Union to be much use, others may find their inclusion of health benefits and workplace representation far more beneficial. In my case my coworkers, the few there were, were quite friendly and supportive, even on busier days. Once you've put in your time for seniority you'll have a more flexible schedule, which comes in extreme handy when you need a day or two off for whatever reason. My senior manager was extremely sympathetic, respectful and ready to work with me so I could further work with the company. If you are a 'people person' with a great work ethic then Safeway is a fantastic first job.
Kontras
Be prepared for customers to find you less worthy than the dirt they trod upon; senior citizens in particular proved to be extremely rude towards the people hired to provide service. Depending on the store location fellow courtesy clerks can be few and far between, in such a way where it may fall on you to pick up multiple peoples' slack. Because pay is based on a union scale, raises are few/far between, and promotions are far more competitive.