Pros: challenging, exciting, decent pay and benefits, wonderful if you're a true believer
Cons: office politics, work/life balance
Day in and day out, the labor movement marches forward. The workhorses of it are the Organizers. These are the men and women who work with the membership every day. It means long hours, hard conversations, a lot of travel, and sometimes very little rest. However, this is not a problem if it is something you believe in. When workers begin to realize their own power, and it is you that empowered them, there is hardly a better feeling in the world. Also, most of these organizations practice what they preach (good wages, benefits, and job security)
Now for the rough stuff. There are a lot more politics involved than almost any other job. You can and will come across some unscrupulous people, both in and out of the union itself. This is not always the most stable way to make a living either, so if you are the type of person who prefers a regular 9-5 job, you won't make it for very long. Sometimes days off can be few and far between (think 2-3 weeks sometimes). Also, you must be able to fight off burnout.
Overall, a decent employer, one I would certainly recommend to someone looking for an exciting, challenging, and rewarding career.