Because it's not one of the larger biotechs, it can be more nimble making decisions (less red tape) and can be more aggressive in its hiring and retention practices. Compensation always seemed slightly higher than the norm in general. Professional yet not stuffy environment. Casual Fridays. Pay Day parties in the office at least once a month with beer/wine/catering brought in. Because of its size (around 200 people, give or take) you get to know people well. A lot of young staff - often hang out together outside of the office. Even older staff are embraced and appreciated for their contributions. Competitive benefits package. Mission driven company.
Cons
Again because of its size and relatively young staff, it can occasionally get clique-y, but never in a harsh way where anyone would feel unduly excluded. Inevitable office politics that can crop up in smaller circles. Some would say favoritism by managers would occasionally come into play. Scientists and business staff work on different floors so you have to make an effort to get to know people in the other teams/departments - there's not a lot of natural cross-pollination.