Pros
The culture has always been employee first. They preach & teach professional & personal development. The compensation is fair. The work life balance is excellent. I've never been and didn't know of anyone who was ever turned down for vacation time or to leave early for a family event.
Cons
Things have started to shift in the culture from open communication to confused communication. Many of the front line and middle management employees weren't sure who to report to or were told to report to multiple people. People are being promoted based on their friendships with the executives as opposed to actual achievement. SEI is being viewed by many employees as becoming an "HR state". Things are much more tight lipped than they used to be.