Pros
The work can sometimes be very meaningful. Most of the people are great. Many departments take part in the flexible schedule program, allowing for comp days on Mondays or Fridays. There's a massage therapist on site once every other week (and SHRM subsidizes a bit of the cost), there's a yoga instructor on site twice a week (and SHRM subsidizes part of the cost), the DAC (Diversity Advisory Council) holds quarterly events and has brought in some great speakers in the past (like Allyson Robinson from the Human Rights Campaign).
Cons
There's been a lot of change lately: three chiefs (CEO, COO, CMO) have left SHRM in the past 6 months, the strategic business review has brought an upheaval to the organization as a whole, and many employees have been moved around to different cubicles, floors, buildings because of org chart changes. More emphasis is placed on revenue than is warranted for a non-profit, and meeting the numbers seems to be the primary goal (even though SHRM is a membership organization) - even if there are not enough resources in place.