With the style of organization it is, you're often subject to the will of the customer. Sometimes customers are tough or unreasonable and you don't have much recourse. Be ready to "put your ego in the trunk" in some circumstances.
If you thrive on process, be ready to be a change agent. Smart processes were embraced when introduced thoughtfully, but at the end of the day, AE is a get stuff done culture with a strong positive bent.
Cons here are really subjective. It was a great place to work and I would absolutely recommend it.