Pros
State Farm has great benefits---health and life insurance, time off, tuition reimbursement, paid educational opportunities, etc. The pay is good for the position, and raises are usually better than most other companies. Jobs are more secure there than most other companies, and there is definitely room to grow. I've never seen a company that encourages self-development more. There are so many different departments and positions that it is possible to have an entire career there and never stay in the same position more than a couple of years. Additionally, corporate employees get to enjoy State Farm Park.
Cons
It can be difficult to move up from an entry-level paraprofessional position to the next level. The competition is high, as everyone is in the same boat as you, hoping that their foot in the door will help them move on to a better position. Many people are successful, but many others (such as myself) give up and go to a different company. There is also a definite "State Farm culture," and you have to play by the rules or there isn't much hope of moving up within the company. Cons vary by position, but the cons in my position (call center) was that I had to deal with customers that were often upset and/or rude, and high call volumes and low staffing often meant that time off was denied.