Pros
People treat each other with courtesy. Every conversation is calm and friendly. It would be weird and inappropriate at Mercer, to express anger or put anyone down with harsh language. It's a professional organization: people do their jobs, with relatively little politics. Women do well there, hold many advanced positions. Norwood has a fabulous cafeteria. The bonus amounts to about 8-13% of your salary, depending on how well the company does and how well you do. They paid the full bonus in 2009, a tough year.
Cons
The politeness can get in the way of getting work done. "I need this done TODAY dammit" would never be said and probably would not get the desired result. Career advancement gets "official" attention from HR and you get emails about it, but in practice it's all very vague, and they tend to fill higher positions from outside. They use a management-by-objectives set up for the bonus evaluation, where the corporate goals are spelled out, and we are supposed to identify activities to help meet those goals. It didn't work for me: my work had almost nothing to do with the very-high-level corporate goals (I was far from the top). I got a bad bonus after several years of good bonuses, when I got a new supervisor, who seemed to select me from the outset as the person he would ding that year. Managers have to put someone in the bottom category each year; I was it, that time.