Pros
You can expect to work with a team of talented, witty and ambitious people. If you are looped in with the right team and right manager, you will also be able to work on some great projects.
Cons
The firm supports a competitive spirit, but it does not necessarily support a collaborative environment. You have to get in there, dive in and hope to fit in. If you don't, it will affect your day-to-day interactions, mobility within the company and the projects you are assigned. In terms of skill, you can learn a lot there, but not when it comes to new campaign models. They have built a solid strategic planning model they can teach from, but it is too static. If you are a person that has more experience in creative/grassroots environments, it may not be for you.