Irregular shifts. Lots more hours during the busy season but a definite possibility of having no or little hours during the other months. Also, unless you keep your availability completely full, you are not going to get the hours you want. But with the money you make here, you'll probably want a second job.
15 minutes early to shift mandatory. Lack of meal break, though you are paid for the time you don't get a break. But honestly I personally don't think it is worth the lack of break.
Benefits don't exist unless you work over 30 hours, and that's hard to get unless you're scheduled regularly.
Communication between mobile, the guards and the office is not great. The office often does not know what goes on at a site, nor does mobile and if a guard runs into issues you essentially will have no help from this end. Count on your co-workers from other related sites or the guy who trained you to bail you out.
I have yet to get any feedback on my performance and the only feedback I get is from Ops and from the office in regards to time and checking in. If you're on time, always checking in and don't leave early then they'll love you no matter how your work ethic maybe.
There can be drama in the bigger sites with more employees as well as the usual "Who do I like better?" game from supervisors. I was offered positions at sites that were "higher" paying but then never got trained on the sites or was only give 1-2 shifts a month despite being trained.
Long hours and overtime averaging agreement. This averaging agreement honestly doesn't give anyone incentive to work these hours for you.
Scheduling errors from time to time. Always be on top of it.
I have yet to receive any promotion, and was actually told there would be a review regarding wages after 3 months, which never occurred.