Pros
Especially if you want to be involved in the nexus between technology and policy, this is the place to be. CDT attacks a diverse set of problems and requires skills in law, politics, and technology. Their projects range from civil liberties to cyberbullying to new internet-related products - which if you're a generalist is something you'd look for. The deliverables range from reports to research to legal documents. And on top of it all, you get to meet some extremely intelligent people both within and outside the company, and you get to enjoy a very relaxed, friendly office atmosphere that's warm and fun to be in!
Cons
Of course, because it is an advocacy organization there are lulls in work, especially over the summer months when Washington DC takes time off. Besides that, some of the work can be not challenging, which may be annoying - but it's something you'll experience in every office.