Pros
Small company, the stores are individually-owned franchises. Work environment depends on the owner. It's a great place to learn many facets of what small business owners need day to day. It's a good jumping off point for perhaps a better paying management job elsewhere. Or, depending on the owner, potentially get into buying your own location if the current owner is looking to get our of the business (and if you have the assets to buy a small business).
Cons
The general public believes you are responsible for the whereabouts of their Amazon packages. This is a common misconception that leads to angry "customers" that really are not your customer. This leads to doing customer service work for UPS but you don't get the benefits or pay of a corporate ups employee. Many other instances of UPS taking advantage of the franchisees and their employees. They use the stores as an almost no-cost-to-them warehouse and are whittling away at the store's customer base by undercutting the stores and stealing customers.