Pros
Challenging and supportive environment: things move fast and you need to keep up, but you're given what you need to do that. Work with good, smart people and for good, smart clients from all over the world. Responsibility is given without micromanagement, so it's a great place to stretch yourself and own your work. Work-life balance is genuinely respected, so you're not taking work home with you (literally or in your head).
Cons
Not really a con, but you need to learn to be comfortable not knowing (and saying it) so you can learn about whatever it is. It's a very honest and transparent culture, so you need to bring that too.