Ventajas
Probably the smartest and best UX people in the business. Creative is OK, but not necessarily groundbreaking. In NYC it's recognized as one of the "best" agencies. Reporter is the best time/budget management tool in the industry.
Desventajas
It's a highly political environment. If you're not liked by or "friends" with the right people from the start, you will never touch a worthwhile piece of work. Hours are unsustainable. Expectations placed on Account and Production are highly unrealistic. Client relationships are hostile and it's considered normal to be lashed out at on a regular basis. There is no cross utilization between teams, you only work within the group that you're assigned to. If your group director doesn't like you, you work on nothing until you're fired.