Since the UPS Store looks almost the same as UPS (without actually being the same company at all), you will often become the target of disgruntled customers, even if their issues have nothing to do with your store. And without much support from UPS, there won't be much you can do to help them.
Most (if not all) stores are private franchises, each with their own pricing, services, and equipment which proves to be frustrating when dealing with customers that have visited other stores in the past.
Mediocre opportunities for a career unless you work for corporate.
The line that separates The UPS Store and UPS Shipping is incredibly blurred and knowing who to ask for help proves to be a big challenge. The information you receive from corporate and UPS customer support when dealing with issues might differ. Most of the documentation available for information is dated and most likely not accurate anymore.
Pricing negotiation can be a challenge due to high corporate fees and increasingly cheaper shipping methods offered to clients online.
When shipping items from your store, UPS will often deny any responsibility for late/lost/damaged items, leaving you to explain to your clients that no compensation can be offered.