Pros
If you are one of those who can manage to pass blame to others in order to keep your job, this environment is conducive to such behavior. Once you have your foot in the door, it is easy to be given a chance to try a job and learn it in the process. If you are still on the outside, it's very hard to get in. Start with a really low position then show your other qualifications, it's easy once you are in. If you learn to stay out of trouble and stay under a good boss, there's a high chance you can remain protected. If that boss leaves, you might want to get a new one who can protect you. Like seriously, your keeping your job depends more on who can protect you than your actual work.
Cons
Because they like to promote from within, they sometimes put highly unqualified people in positions thinking that this will result in something good happening. The result is usually disastrous. They sometimes promote people to high positions without making them learn everything about the positions the new managers will oversee. This results in the managers asking for and demanding statistics which in the reality of the job, mean absolutely nothing. You have to keep quiet otherwise you could be talking to the person who will go to HR and report you. Even those that do their job well, their heads roll from time to time for some bizarre reason. It's a very unpredictable place with reorganizations taking place in departments for the entire time I was there, and I was there for four years. Not a good place for minorities even though the company boasts a lot about diversity. They still have a long way to go to stop making this diversity just window dressing.