Pros
Worked on marketing/growth. High level of autonomy and senior management is very receptive to new ideas. Even as a college sophomore I worked on initiatives with the CEO and was involved in daily discussions about where the company was headed. As an aspiring entrepreneur, the experience was very valuable.
Cons
Small team may not be for everyone and will require that you take the initiative to determine your own objectives. However, skills leant are highly applicable even to a bigger company (two of the interns, including myself, are working for a large hedge fund this upcoming summer).