Pros
Most interesting projects, really smart people, challenging everyday. Not for everyone given the level of challenge and the pace. But the most stimulating experience you could hope for. Very fast pace, so you are never bored. Very entrepreneurial, so the most successful are self driven, self motivated. Benefits and salaries are like nowhere else in the market.
Cons
Hard hard work. Travel, if you are not into it. High demand clients on high demand projects.