Pros
Good benefits. Stable opportunity for unambitious but reliable or people with skeletons in closet who are willing to follow rules and do as told. Good opportunity for very young or single parents. Off time easy to get once probationary period is up. Office environment clean, safe, free coffee, et al.
Cons
Ambitious or creative people will be extremely frustrated. Rules and systems set up for unionized package car and hub workers (referred to as "brownside") imposed on nonunion and actively union-suppressed office workers. Training poor. Rules very extensive and communicated in tedious and repetitive way. Micromanagement is the rule. Supervisors are often dysfunctional people picked for brownnosing-no pun intended. Pay below market. Opportunities for transfer elsewhere within UPS discouraged and denigrated. Computer systems have poor interface, poor reliability.