Pros
Anthem has a very good work from home policy though it can vary greatly depending on what department you are in and your manager. There are overall great benefits and the pay is competitive. There are opportunities to move around the organization to different roles.
Cons
Since it is a very large organization, managerial effectiveness varies greatly across departments. Might be difficult for new employees to adjust without a supportive team and manager. It is highly political among competing internal teams for resources and recognition. If you are middle management or below it is very difficult to be noticed. Favoritism reins. Too frequent organizational changes makes it challenging because of constant shifting priorities. If you can go with the flow you'll do well.