Pros
There are some great opportunities for experince and the management team is open and accessible. People respect them because of how they conduct themselves and it is great working as a team toward the same goal. This is a great company, comprised of great people that deliver an amazing product.
Cons
One of the benefits -- lack of hierarchy also leads to a drawback -- lack of titles. Many that are looking for a title are not doing so because they want to feel important (not that they don't, but it is not an ego thing), but rather most of the company is early in their careers. Chances are, they may have another job or two in the 30 plus years left of their working life and most other companies don't scan resumes in-depth to see what was done, instead they look to see what their position was at their last employer. Also, more vacation time would be great, many software companies give more weeks. Had to at least try!