Pros
Super nice office / valet for work, fellow assistants are great, support staff and director of operations is great, handful of managers are good people who want to mentor. Good name recognition when you are looking to make the leap to another entertainment company.
Cons
your mental health will depend on the manager you work for. I would say 70% of the managers like to make your life a living hell for their own entertainment, so ask around before you accept. They promote an assistant or two every 3-5 years, typically after spending 4-5 years as assistant there. Little room for growth. Also the studio side hasn't made anything noteworthy or even relatively good since the Golin years. It feels like AC is coasting on their Golin era name recognition but the whole of the company is slowly falling apart without the leadership. Also remember HR is there to protect the company, not you.