Pros
Two weeks of annual leave (aka paid time off) was a plus, however you are force laid off for one week every year. This is so the USPS can avoid giving you real benefits such as sick leave, retirement, or health benefits. Expect the week you were hired to be your vacation time from now on.
Cons
I lasted a year and a half. During that time I believe that I had a 40 hour work week twice. Prepare to work 6 days a week up to 65 hours per week. The average was probably around 50 hours per week. Your schedule will change daily. Monday you may be scheduled at 9am-6pm for a window shift. The next day you will pull a 4am-4pm, or 6am-6pm. The work is physically and mentally challenging, which is not a downfall for me usually. You will be sleep deprived, your friends and family will never see you. The PO will be your life. The management/union relationship is tense. The union is just about powerless. They work you so hard, nobody in the local has the energy to fight back. Management's job is to squash the union they will spend their entire work day on it. There are never enough people staffed to do the amount of work that is necessary. Postal workers are the hardest workers I have ever seen. I have worked in Landscaping, Nurseries, Retail, and Restaurants. Postal employees have a stressful environment and work their butts off. I loved my co-workers, very good people but the management makes that place miserable. They have no regard for their employees and the sacrifices they make.