A masters in public health is a professional health degree where most complete an internship of several weeks in a public health agency. Like any degree, I feel the value that you derive from it depends on the type of experiences that you wish to derive while pursuing the degree.
There is one group who already work in healthcare as nurses, doctors, veternerians, dieticians, social workers, environmental safety assessors, etc. and want further training to advance and fulfill their job roles within the public health system.
Then there is another group who wish to break into the public health field in areas such as health promotion, health research including applying epidemiology and biostatistics in public health agencies such as CDC, WHO , etc,
There are some who use the MPH as experience to get into other programs such as medicine , nursing, and law.
As for job prospects, public health field is not always the best funded . I would not be getting excessive loans for a highly accredited mph degree from a Ivy League school. At the end of the day, Passion for public health training and gaining experience in the field means more than just getting a mph. Volunteer work with public health agencies is a way to see if you enjoy working in the public health field and determine whether you wish to pursue a mph as well .
Hope this answers help and if not, I am would be happy to and we any other questions.