Avantages
There were some smart people there, some of the best User Experience folks I've ever met. You get paid a lot for the abuse.
Inconvénients
Quite possibly the most toxic, absurdly ineffective environment I've ever worked in. Account/Creative/Tech blame each other. No one ever says no to Clients. If you're not in the "cool kids" club from before you get there, it's impossible to actually get any work done. Zero Work/Life balance. Take time off, come back to no job. Firing is extremely common, as is swapping out team members on projects, especially when they think what they're working on isn't good enough for them. A culture of backstabbing, lying and finger pointing. Technology is an outsourced joke of "resources" making development nearly impossible.