Pros
Professional growth and career advancement. If you're young and hungry, then this is the place for you. You won't get this kind of experience anywhere else. You can work like a dog for 5 years then leave for a job somewhere "sane." Be prepared to work like a dog for the privilege, though. Enjoy the dinners and events, but understand that your social calendar will be limited to the people you work with.
Cons
While Accenture officially places a priority on work/life balance, in practice, it's completely different. You are expected to "live" Accenture if you want to advance. If you think you can get away with 8-5 Monday through Friday, you're not going to get anywhere. Managers and above are expected to be available during evenings and weekends. Blackberrys are on 24/7. If you're looking for a job that you can leave at 4/5 o'clock and forget about...forget about it.