Pros
There were a lot of great people I got to work with at PP. And the pace of things is fast - you don't get bored. I got to work on some interesting projects. The pay and perks were decent. The strategists in PP know how to make money, so there's no worrying about the viability of the company.
Cons
The company structure is extremely hierarchical and political. Good ideas, good decisions and good people are ignored if they don't orginate from the right level of the hierarchy. There was a lot of blatant sexism and bullying. There often was no recourse for this if the bully was higher up the food chain (see extremely hierarchical). As a result people put up with a lot of behaviour that would get someone fired at a different company. The turnover is high because the work environment is stressful and negative in a lot of areas of the company.