Pros
They do promote from within, and allow you to find your niche within the company. There is a great onboarding process for new employees, and an all around good group of people that work there. You get a lot of visibility into a lot of different processes around the company, and if you are in the right meeting, on the right day, your opinion is usually listened to. There are no limitations of the cross functionality of a position.
Cons
NEPOTISM. If you are not in the IN crowd, you will wonder every day if you have a job. Lots of emotionally run processes, with a lot of protection of the wrong people. They want to 'help' you grow, as long as you do exactly as they want you to do, they leave that up to you to guess though, lots of changing minds depending on the mood. A lot of fear based management, it comes from the highest of the high, so its no wonder that it trickles down.