Pros
It's mostly a self-managed job. You will not have a supervisor constantly on your back. Potential for great benefits (after a year). Great starting salary, without a lot of education or skill requirements. Tons of potential for overtime (during Fall/Winter) - up to 16hrs, 7 days a week (for careers) and 14hrs, 6 days a week for PSE. In the slow months, there's a lot of potential for shorter shifts. You may have the opportunity to leave after only two hours of work. Supervisors are generally willing to work with you, if you have schedule issues. (It's a 24hr facility) The union is there to protect your employment (after you pass probation). You can't be fired at random. You have the opportunity to start as a PSE and transfer to other positions with the USPS.
Kontras
Several managers are rude (and reporting them seems to do nothing). Training is a joke; you won't learn the job until you're working the floor. You're not eligible for benefits until you've been employed for more than a year. At least three weeks in December, you will work twelve hours, six days a week. Mandatory overtime can be called at any time, and during slow months (spring/summer), you may be forced to leave early. Sitting at a computer for hours, with short breaks each hour - and no talking. (A small area is reserved for talkers, but you may not get that area every day.) Lots of red tape. Updates, changes, improvements take lots of time and are sometimes virtually impossible. This position attracts antisocial personalities. Before you're promoted to career, you're expendable, and you will have to wait years before you're promoted. (About two years, at the least, but some employees have waited over five years.) The process to get to career conversion is long and frustrating: First the postal test, then the application, then an interview and group orientation, then two weeks of "training" (You must pass a long series of tests within two weeks - or you're fired). After that, you have three months of probation (where you cannot miss days and must hit certain goals, or may be fired). Then, you have a year before getting benefits, and you have to wait for a career position - but before you're converted, you have to go through another three months of probation.