A PMP is superior to a Masters in Project Management. A PMP represents at least 7,500 hours of actual experience leading and directing projects, as well as an objectively assessed degree of theoretical knowledge. In contrast, a Masters in Project Management is almost purely theoretical knowledge.
The first attempt pass rate is 60 to 70%. One way to increase the value of certification would be to increase test difficulty so the pass rate is decreased to the max. 50% on the first attempt.