Pros
Strong benefits, good HR team, great offices & casual work environment, strong corporate focus on improving the product and technology, nicely hungry to continue to innovate the company (not complacent at all), very data driven in their decisioning.
Kontras
As others have observed, there's a long history of regular re-organizations -- you can count on a big re-org descending about every 6 -12 months or so. This results in lots of change in leadership team members and difficulty maintaining momentum and strategic focus / direction. Play politics become more important because you have to plan for being positioned correctly for the next re-org. Compensation is good but not great, due to the big competitors for Seattle employees -- Amazon and Microsoft -- having more employee-friendly philosophies toward comp, especially granting stock option to a wider segment of staff members, not just for more senior roles.