Pros
The company is very serious about personal and scientific integrity. The work culture is one-of-a-kind; I've never seen so many people truly enjoy working with one another. The managers are interested in you as a person. My experience is that if you express interest in developing new skills, you will be encouraged and supported in the fulfilling those desires.
Cons
Whatever the formal structure may be, the company hierarchy is flat, informal, and fluid. This is great and empowering in many ways, but it also presents some challenges; it is easy to feel as though you are simultaneously responsible to everyone and responsible to no one. Some might have a hard time with this. But anyone with initiative will probably thrive in this environment.