Pros
The people are very, very smart, motivated, and hard-working, my group at least thinks a lot about management and how well managers are motivating and developing their people, and provide me with great role models and mentors. The work itself is fascinating, with meaningful problems. It almost always feels like a meritocracy - so good performance gets rewarded and poor performers get weeded out. It can be hard to maintain work/life balance, but you always feel that on a basic level, people support your efforts to do so, so it's more you struggling with yourself and letting yourself say 'no' and maybe give up opportunities than feeling like it will be frowned on or you won't get other opportunities later if you do.
Cons
Everyone works hard, it's a challenge to maintain work/life balance