Your opinion is listened to which could potentially change the course of projects, policies and plans as a result.
Your contributions are recognised and efforts rewarded.
You learn everything from the ground up and as a result you tend to wear many hats but learn loads.
Your team becomes your gang!
Cons
You have to learn everything yourself there are no departments to fall back on.
You actually have to work hard, there is literally nowhere to hide!
You are on call 24/7 when there are deadlines or emergencies.