Large organization; Some very good people, some not so good; Management and culture doesn't distinguish between the two.
Pros
For projects that Apple upper management has its eyes on, quality is given high priority. Teams on those projects are also often very good, with smart and experienced people with whom it's fun to work and from whom one can learn at lot.
Cons
It's a big place, and there are sometimes inefficiencies due to the number of people involved with a project. There is a significant amount of politics involved with promotions and a significant amount of empire-building, with teams growing unnecessarily to bolster the team managements' prestige. Projects that are not visible to upper management suffer from quality problems typical of any organization, but everyone is very confident about the superiority of their work regardless of their actual performance and the actual quality of what they produce. Arrogance is rampant and encouraged by management and the corporate culture.