Pros
There seems to be very little risk of actually losing your job - they tout a high employee retention to their clients and like to keep it that way. Friendly atmosphere - division events, recognition for service, awards, etc are a nice gesture from the company; and the people are generally friendly and pleasant to work with Great pension and retirement benefits. I can see why some people stay for 40 years. If you want a stable, boring job with high employee retention that will allow you to support a family, this is your company. It's certainly not for everyone, though. If you are a recent college grad: there are a lot of worse jobs out there. I've found that my professional development has been stunted a bit at Securian, but it's a low-stress job with good pay. Weigh your options carefully :)
Cons
Conservative culture - not keen on trying new ideas. Too much management - hard to say if this is just my division, but there are layers upon layers of management, so they end up spending their time taking 2+ years to do projects that really should be done by teams, quibbling over budgets, or arguing in meetings. Gossip - this one has been shocking to me. I'd say it's worse among managers than it is on the teams. They throw each other under the bus all the time. Oh, and they talk about employee's performance to other employees. Time seems to move slower here - perhaps not for your daily job (depending on what you do), but projects, individual growth, promotions, and new ideas seemed to move a lot quicker at my old job than at Securian.