Ventajas
UPS, like many companies, believes in promotion from within. It's the kind of company that you should work for if you're looking for stability or a place where you can work for the rest of your life. Their benefits package exceeds that of most employers. They still have a pension plan, which is rare. In their entire history (since 1907) they have never laid off a management person. There are plenty of different career tracks that a person can take at UPS to tailor to what you want to do. They have a good amount of personal time and vacation -- they start all employees with two weeks and five personal days. There is a great deal of flexibility if you get in the right department.
Desventajas
As far as learning and development, UPS isn't the best place to work because of groupthink. Most of the management people, even every CEO they've had, moved up the ranks within UPS, which doesn't allow for a broad range of ideas. Most of the upper management I've encountered are very set in their ways no matter how idiotic. There is a great deal of hostility because it's a traditional union versus management environment. Depending on the department, they make take advantage of lower ranking people by giving the same amount of responsibility for much less pay. There is also some racism and sexism with the older senior management. There isn't a lot of direction and most of the time it's a "sink or swim" environment. Many times they promote someone and don't provide the guidance that one would need to succeed. You may be required to work third shift.