Pros
A tightly-knit talented group of designers that are all giving 110%, I can't think of a better place to cut your teeth in the design industry. The way it's structured it's easy for anybody to contribute to a project, concept, or strategy, regardless of their position or seniority.
Cons
Project timelines can be tight which constrains the amount of work you can put into a project, but on the plus side this means every month or two you've got a whole new design challenge to work through.