Pros
It can be dynamic, creative and highly entrepreneurial, and even exciting at times. Ultimately, it's a very meritocratic environment -- good ideas go far and creative bubbles up from the lower rungs. For kids starting out fresh from college, it's a boot camp that stays with you for the rest of your career and you will learn tremendously. Some of the creative execs are among the best in the business, and as corporate environments go, the diversity is a welcome alternative to the white Ivy grads inundating other companies.
Cons
The same spirit of entrepreneurialism has its inherent drawbacks: senior leadership is MIA, report structures are a complete mystery, internal resources are squandered on conflicting priorities, direction changes all too constantly, there's very very little communication, and executive accountability to the troops is unheard of. Senior execs institute staff purges while maintaining sick expense accounts. Helicopters to JFK are not unheard of and yet the $100 a day assistant has got to go.