USPS delivers a mixed mailbag.
Pros
The stability of its pension plan and retirement benefits are a very positive aspect. These are unlikely to change and ordinarily there is little down side risk of involuntary separations, making it a very stable workplace if you are willing to accept limited opportunities for career grown.
Cons
"Diversity" is pushed to the point that highly qualified Caucasians are by-passed to increase the number of Blacks and Hispanics in supervisory and executive positions. Another drawback is that down sizing of the Postal Service is inevitable because of mail volume declines. For the few who are hired, increasing workload per person and turnover in personnel create undesirable churning that can make tough jobs even more difficult (no, I won't use the politically-correct word, "challenging")