Pros
If you want to wok in progressive organizing, this is a good place to work. The company recently put a lot of effort into improving and standardizing pay and benefits across the board. Salaries are now open throughout the company. There is little micromanaging; you're expected to work independently and to move up the ladder as you learn more skills. Lots of opportunities for growth. Most people are friendly and supportive. Both offices get together for a early retreat. Great flexibility in terms of working from home and telecommuting. Note that offices are in Berkeley, CA and Washington, DC, with additional staff around the country.
Cons
Depending on your clients, you might be overworked, particularly in the weeks/months before elections. There is an expectation that you be available at all times. Some managers are not good about defending junior employees from overwork or abusive clients. Some more progressive people might be unhappy with the moderate clients and the frequent work with real estate developers. Less progressive people will be unhappy with the extreme left-wing partisanship (if you want to reach across the aisle or live and let live, save yourself the trouble of applying).