Pros
Principal Financial is a great employer because they take time to listen to employees. Twice a year there is a Town Hall style meeting with senior management to ask them questions. The benefits are almost overwhelming at first, especially since they offer coverage for domestic partners. The society and scope of the company is large enough that anyone can fit in any where, but not as corporate drones. Every one is encouraged to volunteer in the community, better themselves through the education tuition reimbursement, or any number of ways. Plus, the headquarters is located in downtown Des Moines, Iowa, a fairly up and coming midwestern population center.
Cons
Sometimes you can get stuck in a department that you don't like, but with the size and scope of what Principal does, it seems sometimes the company molds to the individual employee to make it better.