Pros
The creative work and exposure to a wide variety of the top companies is incredible. People whom work here are very highly skilled and usually in several areas (ie: strategy, consulting, design, emotional intelligence). Teamwork and authenticity are huge here. If you're a lone wolf type, this is not the place for you. The company doesn't just pay lip service to work-life balance and there's a culture of excellence in everything you do. This company is very tip-of-the-spear in approaches and in thought leadership. Employees are very passionate.
Cons
Getting integrated into the corporate culture can be overwhelming (although it is well mapped out and very actively managed with hands-on support) simply due to the sheer volume of expertise needed in order to be fully functional in front of clients. Passion can sometimes cloud objectivity but they handle it well. Quote from Sr Management: "Inside these walls there is only opinion. Facts come from our clients".