Good for some, make money, get experience and a clearance.
Pros
The work isn't hard to make a lot of money, especially for night shift. Day shift is a little different, often busier and can be hot with little rest or interaction. Your location and specific contract dictate the quality of the job. Some supervisors make and enforce absurd rules, some are cool and don't make you want to leave. This job ranges from absurdly awesome to tedious and political, again depending on your location and supervisors. Pay is usually pretty good, and it's a decent environment.
Cons
There's a reason this company pays so well. It's because they make a lot of money they want to keep, but nobody will stick around if the pay isn't high enough. Pay is most of how they keep employees. Go into it well-informed with a sense of reality. It can be rough, but it's what you make of it. The restrictions on not sitting or talking or sometimes having water and various other things can make this job go from not bad at all to a rough experience. There are a lot of yes-men in supervisor positions who will make and enforce rules for no reason. Unfortunately, as with any big organization there are a lot of people trying to get away with bending and breaking the rules for childish reasons, which means everyone has to suffer when the rules change because someone fell asleep sitting on a stool. Now nobody can sit aside from breaks. Not that terrible to me, but after a few months it starts to wear on your body a little bit. Some people work there years and never notice, some people get legit injuries from standing for over 40 hours per week. You are constantly subject to schedule changes and can be forced to stay with absolutely no prior notice. You can have your off-days taken away at any moment. Just the nature of the beast, working security. A lot of positions aren't bad, and if you stick with it you have a chance of getting a good position if you're decent at simple tasks. Otherwise, if little stupid things don't bother you, this could be a great job that takes a while to get to you. Biggest difficulty is that some schedulers won't work with you if you have classes or whatever, the skills have limited transferability, unless you want to stay in police/security/Law enforcement. Not the worst job, but there are unfortunate things that can compound to job dissatisfaction if you don't make the most of it. Drove me kind of crazy how mind-numbing it was. I like to think and put my skills to use actively every day, so this was a bit soul-crushing at times, but you find a way to make it work.