Pros
One can learn good clinical trial management skills. Friendly, loyal staff. People work hard. People responsive and willing to help. Structures change often so able to get exposure to different things quickly. Company culture evolved around founder, so is cultish. Founder billionaire Brit, so was a bit of a monarchy with lords and fiefdoms. Nepotism and favoritism rampant. New CEO from Accenture, so culture shifting but not necessarily better - colder, mechanical and more uncaring of people.
Cons
Little development. Life work balance ok. Tension and anxiety lies just below surface of joviality and camaraderie . Cultural class between new employees and old. Not a high integrity organization. Prefer to follow the leader than stick neck out. Big difference to your career if you are liked (regardless of skills) or disliked (regardless of skills). Company tries hard to push "best place to work" and overall company image. But these stem from the cult culture and are mostly paid for promotional and lobbied rather than reflect fair polls and actual reality.