Pros
There are some great people to work with. Some of the technology is really good. There are some very interesting and complex problems to work on and solve. You can easily have direct access to anybody including the CEO if you like.
Cons
Continual turnover. VPs have a very short shelf life outside of the founders. You should not plan on a long stay, especially if you are in a management position. Certain positions have no hope of getting positive recognition as they are not valued, such as marketing, product management, program management, and QA. There is a very development centric view, all the way to the top. The CEO does not put people in place and expect them to own their area. He will often get involved in the tiniest details of any functional area rather than working through his managers. He also frequently entertains direct complaining from almost anyone. This leads to a lot of office politics and no real authority for management positions. It also means the CEO is not spending enough time doing his job. Increased competition in the space has pressured growth. The company needs to find a way to successfully expand into new areas in order to meet its goals and give value to the equity.