Pros
The work championed by this organization is vital; through it, Swanee Hunt (the founder and head of the organization) has effected change for women around the world. The organization and the employees are well-established and well-connected.
The company consistently hires amazing people - the staff is talented, intelligent, driven, and fun. The company also trusts the people it hires; on the whole, you are given freedom with how you get your work done. That being said it's not totally hands-off; most coworkers are very happy to help and support each other when asked.
Swanee herself is incredibly smart, driven, and hardworking.
Cons
At the end of the day, Hunt Alternatives is an autocracy; Swanee Hunt is its head, and her will and whims dictate the direction of the organization.
Swanee is in the center of a multi set Venn diagram's worth of poorly managed personality and mood disorders - the most impactful for her workers being that she exemplifies narcissistic personality disorder. She also has almost no concept of time (she cancels or is very late for internal meetings about 85% of the time, and she generally underestimates how long things take by at least a factor of 4).
The CEO is smart and shrewd with impressive self-preservation techniques; it's unfortunate that she consistently applies them only to herself rather than the organization at large.
Due to this, the environment can be very erratic, and it can be very difficult to move things forward. You need to watch your back, make alliances... it's honestly kind of like being on Survivor.
Overall, this job is what you make of it - if you keep all these cons in mind and set good boundaries between yourself and your work, it can be a great place to advance your career. At least until the next round of layoffs...