At the end of the day, everything comes down to how they treat their staff. They do not care about their staff at all. I've only worked for 3 security companies, and this one was by far the worst - the supervisors and managers only talk to you if you make a mistake, usually it isn't even something they explained to you in the first place. The site i worked at had no training at all, but lots of ways to make big mistakes.
There could have been good things about this job, but when you feel like they are taking advantage of you it isn't so good anymore