Pros
Given great autonomy to form your own core group of volunteers. This provides you great people with which to work. They provide good benefits, but it is over as soon as you exit their employment. Salary can get you by in your basic life.
Cons
The hours can be grueling. Although, this is generally during the weeks leading up to the election. Management can be awful. They don't take an active role, so they have no way to support you when needed. The organization itself is not central at all. Many different departments working towards the same goal, but in different ways. Non-field employees have not worked in the field, so they've no idea what resources you need. Creates much frustration. Salary. You are told there will be options after the campaign within the administration or they will work hard to find you work, but that is a lie. They use you and leave you to die on the hopeless job market. Remember, campaigns are insane. 3 months from the election, you will not have a day off until a few days after the election.