Pros
There are plenty of training opportunities, or on the job/in role learning opportunities, working with some very good people. You can gain great experience through exposure to a varied and interesting customer base. If you put the effort in, and are a self starter, there can be some good recognition for your services to the company as well.
Cons
CC is very sales centric; the bottom line is the bottom line. Consequently the customers are always put first, with employees coming in (a close) second. Mostly this is a personal thing, some prefer this, other want a different corporate feel. It's somewhat subtle, because there are good opportunities to be had, but it has an impact on the feel within the organisation. The personal other point when considering working for a company like CC is you are the product. This also has an effect on the company culture, and is important to consider if you have a background with a vendor for example.