Pros
steady work and hours, over time is always available even if you just worked two 16 hour shifts back to back. An assigned post is normally 8 hour shift but you might be held over for a no show relief. Generally looking for warm bodys to fill positions but easy to get a job with prior experience or military/ police background. Very hard to get fired you will just be shuffled to another site.
Cons
raises are rare and there are so called "post specific pay". if you move to a different site you can get a pay raise or cut depending on the site. Its possible to get around this by being a rover or working two posts. Rovers are called at any hour of the day unless specified otherwise by the rover and even then sometimes you can get a late call. As a rover you can be called to be on site in thirty minutes sometimes for a no show guard but going in is optional.