I have had a pleasurable experience working for the USPS. Some people have not though. However, in all jobs there are Pro/Con's. If the organizational culture fits your personal preferences then the USPS will be an awesome place to build a career.
The USPS is a honorable job who’s purpose is to serve the community. The benefits are excellent for full time workers. However the assistants ( or part timers) do not qualify for disability, unemployment or sick leave.