Pros
Application process ensures that only experienced professionals get the job. Managers do not incessantly call or look over your shoulder during a shift.
Cons
Pay! MPS lost a contract a few years ago, so there are senior people who were necessary when there were more staff, but not any more. So, no matter how much training and experience you may have walking into the office, you will not earn more money than the guy who has less to offer but has been around longer.