Pros
You've got the freedom to chart your own course and decide how you want to grow, either in your role or in a new one within the company. Freedom, to an incredible extent, to choose when, where, and how you'll get your work done (using good judgment, naturally). Freedom to be yourself, which I particularly appreciate after some of the more oppressive places I've worked. Play to your strengths and find a way to make your strengths benefit your team and the company, and you'll love going to work every day.
Cons
This much freedom isn't everyone's cup of tea. You do need to be able to chart your own course and define what success means to you. Huge progress has been made in helping employees grow and learn as they take on new roles, but you still do have to do a lot of the heavy lifting yourself. But that's the tradeoff of a place that treats you like an adult -- you have to actually act like an adult and make things happen. It's a price I'm quite willing to pay.