Pros
Even when I was a new employee I felt my opinions were welcome and appreciated. In just a few years at Gallup I have gained opportunities and responsibilities in things I'm passionate about and that align to my talents. Strengths-based culture makes everything less competitive and more collaborative -- I love being able to call my colleagues "friends." Managers set goals with you, but they trust and empower you to achieve them in your own style without any annoying micromanaging. Because of this unique management style and culture, Gallup is definitely not for everyone -- If you don't come to work "ready to play" and make things happen, you won't last long and you will have difficulty achieving a healthy work/life balance. BUT if you are a hard worker and a team player you will be rewarded and have a fulfilling career at Gallup.
Cons
Sometimes the hours required to be productive and "successful" can get a little high, but most of this can be managed by having open conversations with your manager about prioritization and ownership of tasks. I disagree with some of the metrics that determine "performance," but to me the pros (culture, flexibility, career opportunity) outweigh the cons for sure.