Pros
The workplace culture at GSG is, in my experience, unparalleled. Almost everyone is passionate about what they do and holds themselves (and each other) to high standards, but there is a lot of flexibility and you're trusted to "be the boss of your own domain." There is very little red tape. Projects move quickly and people are receptive to feedback, whether it's about the product, processes at the company, or your own role. There is a very good work/life balance. My impression is that most people work just about 40 hours on a typical week and probably average a little over that, excluding time off.
Cons
Different teams and roles are different, so your experiences may vary. Different teams have different amounts of central coordination/management, ranging from what we call build teams, where I probably could have missed work for a week and no one would have noticed, to implementation teams, which some may perceive as micromanaged. But this is mitigated by the flexibility in assignments, so you can generally move to a role that works for you. Roles tend to be a little narrowly defined compared to similar companies I've seen. This is a benefit for many people, especially if you've had issues being overworked. If you want to be doing customer support, internal projects, and development at the same time, this is doable, but will require fighting the current a little.