Pros
The only reason I gave 2 stars instead of 1 is because my first year there was great. I was properly trained at my site (no thanks to Universal, just 2 very amazing senior employees who loved what they were doing and were happy to teach) and everything went well. Everyone at that site was great and we had each other's backs. All the other sites have little leadership or supervision so you can do as you see fit as long as you keep the site secure.
Cons
Little supervision also means bad communication and no one really knows what they're doing. There's no respect for the employees no matter how much time you sacrifice to help out. If you can't make it in to cover a shift because one of your incompetent peers called out, prepare for the biggest guilt trip of your life. Some scheduling people don't even bother to call and "ask" if you can cover a shift, they'll just stick you on the schedule and hope you show up. When the job goes good you'll get $10 an hour with no thanks, when the first tiny mistake is made you're blacklisted and given terrible hours at sites nobody wants. Or they cut your hours entirely and hope you just quit so they don't have to pay out any unemployment.