Pros
USPS has a lot of great employees who really care about their work and want to do a good job. I've met great people at all levels and in all geographic areas. There are a lot of career opportunities once you get into the company, since there are a large variety of jobs (almost every job you can think of!), and most managers are open to allowing temporary assignments so that you can learn and experience different jobs. They are committed to their employees, so all jobs are posted internally before they are made available to external applications, and they will work to help you find another job if there is a restructure in your group; they actively avoid laying people off.
Cons
Due to the economy, USPS is constantly trying to do more work with people, so the jobs can be demanding and those who care about their work (which is most of us!) find themselves putting in extra time to get the work done. Also, although there is a large variety of career opportunities within USPS, you may need to relocate to take advantage of them. For example, headquarters is in Washington DC, so if you are in the field and wish to continue moving up within the professional areas or management, you will open those opportunities if you are willing to relocate.
