Pros
+ Very smart people -- people aren't only smart intellectually; they are also fairly diverse, so you can actually start to live a normal "life" even if you hang out only with work friends. + Opportunities are easy to come by if you are: a) Able to prove that you can get stuff done, and b) Driven to find the opportunities. All you have to do is ask.
Cons
- Often, it is easy to lose sight of the personal life of people. Most managers are all of the same kind -- the personal side of the employee comes much later in the decision making process unless the employee puts it front & center. - The "NPI"s will often derail the best carrots put in front of employees; a project that you were looking forward to this year will often be delayed by a year because of something else that is necessary for the company.