Pros
An awesome place to work if you want your day to day work to be varied and constantly changing. You are given high level responsibilities even at more junior/mid level positions and asked to grow into them, you learn a lot very quickly and have the freedom to craft new ways of working and thinking about growing client's businesses. There is a strong emphasis on professional development and a generous budget to pursue whatever is interesting to you if it can help you internally or externally. There is a high degree of freedom and you never feel like someone is watching over you. The only expectation is to produce high quality work and push the thinking of the team forward. If you do that you are rewarded with more responsibility and people management opportunities.
Cons
If you need a high level of structure in your role, P+S is a difficult place to start. If you are looking for a place to be an intrapreneur and see a direct impact as a result of your work it is an awesome place to build a career.