Pros
Great work/life balance and benefits package, including a pension. There are lots of people who have been with SF for 20+ years, and it's real tempting to stay here for all the perks. Everyone is friendly; they hire good people and try to foster a community atmosphere in the office. Lots of talented people to work with. Flex time is best time. Lots of training and education opportunities. If there's a problem with your performance, they'd rather make you better than fire you. Work from home is often an option (but fully remote worker is very rare) The rules of the corporate ladder are made real obvious and fairly easy to follow, if you're in to that kind of thing.
Cons
A lot of the pros I listed only apply to tech folk. The Systems department is basically a separate company with its own rules. I've heard mixed reviews from friends in claims, legal, etc. Even in Systems, a lot is left up to "manager's discretion", which can be good or bad. Pay is lower than industry average. They make up for it with benefits, but some people would rather have a bigger paycheck than services like TeleDoc or gym membership discounts. Big cogs turn slow, and often. Some tech decisions are lagging behind the industry, lots of waste and absurd restrictions. Meanwhile mid-level managers are in constant churn - usually to different depts instead of leaving. Pretty much have to play the corporate ladder game to advance in pay and be taken seriously by higher-ups.