Pros
The clientèle is amazing, understanding and patient. You tend to grow into a family feel in the UPS stores with both regular customers and colleagues. The environment is very relaxed and you receive a lot of help in the beginning to learn and if you pay attention, you can learn extremely fast and, if you watch your managers very closely, you can learn faster than the time they expect you to learn in and more effectively. The testing you have to do even in the store assures you that you know exactly what you are doing and brings a great self-confidence along with allowing the company to know that you know the job very well. The pay is decent as a first job or a second job to help with expenses. The work is not hard at all to do. If nothing else, this job is a great company to add to your resume!
Cons
(This is from personal experience and only with the store I worked at, as far as I know) The hours are not flexible at all. If you need time off for injuries or illness, you tend to lose your job in your absence. If asked to amend the job due to an injury they are unwilling to comply and tell you to take the time off. The store is unwilling to back up claims of rule breaking with evidence when asked. (one specific situation was a simple glance at the security video). It is difficult to work a second job with this job and they are unwilling to schedule around your other job or classses. Ability to advance from a store associate is difficult, though not impossible.