Pros
Since there are so many things against u in this company work wise, the only thing that stands by you are the people that you work with. Also since the top n middle management team are busy "delegating" their work to people under them all the time, there is a lot of exposure towards acquiring new skills. I would say its a good organization to start your career as here you will learn a lot of tricks of the trade to get your work done somehow.
Cons
Well to start off, they are one of the worst payers. Their annual compensation is the least when compared to their competitors. And to add insult to injury, there is no true values and work etiquette. Work pressure is immense work pressure. The company does not value their peoples lives and expect you to slog endlessly for their own benefits (which is the case with other companies as well, but the worst thing about Sitel is that they will make you know it as well).