Pros
The organization is incredibly open minded to entrepreneurial individuals. If you have an interest in something, and can show that you have the ability to profitably take on work, most people in leadership will support you. The principals are generally a well-versed and strategic group, who are widely trusted to be driving the company while thinking about the long-term stability and profitability.
Cons
While the flat organization and independent operating structure allows for great flexibility and adaptability, the lack of centralized data management can cause gaps in information flow and inconsistencies from one project/group/division/manager to the next. Similarly, those with an interest in cutting edge technology would likely find the speed to adoption of new project management software in this setting to be stifling.