Pros
Really smart people to work with. Culture shaped by elite consultant types and engineers, all over achievers so the bar is high for performance standards. Young, hard working-hard playing techno -innovator types so your workload is constantly changing, no chance of getting bored. Exec management team is super focused and well respected, good to work with a company that has a great reputation for solid business practices.
Cons
The company runs really lean, it can be overwhelming, never enough time to get it all done. If you're not super self directed and able to plow through lots of work independently, you won't make it. Your managers are also under a lot of pressure so don't expect a lot of hand holding or one on one management. Great if your a maverick by nature, not so great if you need structure.