Pros
Fast paced, ever changing, lots of opportunity to step outside of your normal function if you show initiative, HR is good at screening out jerks which means if you're an adult you will rarely come across a mean person. I found that I thrive in this type of environment. It's not for everyone. As a side note my experience has to do with operations. I know nothing about the call center side of the company so don't relate my positives and negatives to that side of the fence. I've heard it's drastically different though.
Cons
If you can't roll with the tide and not let things slide you won't do well. If you like change you will float, if you don't you will drown. After the hiring process HR is pretty much invisible and getting worse. You have to except the fact that they are there for the company and not for you.