Pros
Clean Water action is really effective at what they do with grassroots organizing and environmental advocacy. They get it done on a very very small budget. A great example of a very accessible organization that puts people over profits every time and encourages as much in public advocacy. If you are political, driven, and bent on making the world a better place this will be a great place for you to start your career!
Cons
Canvassing and fundraising is really really important and necessary work. If you are a person who has difficulty connecting the dots about the need to raise money (unbeholden to corporate interests) to do political work, it could be difficult for you to maintain the motivation to be consistently successful in a canvassing job.