Pros
The company has strong brand equity in spite of a lot of very negative information and reviews about the company online and in the press. It's been a few years since I worked at Gallup, but given the recent reviews on this service and that all the same people are still in charge at the top, I gather little has changed. So if you like a static, stagnant work environment where innovation, initiative and long-term outlook are frowned upon, then this place is for you. And if you enjoy hypocritical rhetoric to the contrary, then you'll surely be in heaven working at Gallup.
Cons
Questionable adherence to US labor laws. No time off of any kind is offered as part of the compensation package. Employees who dare to take time off sometimes come back to work a week later to find their jobs gone or their projects reassigned or high-jacked. The worst thing is the overt discrimination I witnessed here. As examples: I heard black male interviewers referred to as "boys" in a telephone conference call with a female company executive. The company is also notoriously anti-gay, with discrimination complaints relatively commonplace. And from what I observed, it seems like it would be pretty hard to advance or get lucrative projects if you're not a practicing mainline Protestant or Catholic.