Pros
It's a good place to start out, and there are quite a few employees in their 20s. It's a great way to network. Every group I have been in has enjoyed socializing outside of work. They also offer great job security. I don't believe they have ever laid anyone off in 40 years. The benefits are cool too--like their year end bonus system, the company picnic and the health coverage is excellent. The cafeterias have pretty good food at good prices, and the open environment allows for communication with those around you while you are working.
Cons
Little to no documentation makes it very difficult to learn. And you are expected to learn. You can only take so much time out of someone else's day asking them questions. While the year end bonus is highly regarded as a huge benefit, don't be fooled, it falls short of making up for the salary pay cut you take to work here instead of someplace comparable. Also, it takes 5 years to get that bonus up to the point of making up for the lost salary. Some people really know their stuff, but unfortunately, there are a number of people at the company who know very little, even with years of experience under their belts.