Pros
Flexibility in my schedule allowed me to overcome serious family health challenges and loss of family members. My manager came through when I needed accommodations in my schedule to deal with my spouse's health problems. They also showed great compassion during a period when I lost two of my immediate family members. I'm not sure that my manager realized how much that meant to my family, but it was a tremendous thing for us. The company stock plan was a tremendously good investment, and I was able to become an expert in my field, but the most important thing to me was the experience of working with smart, decent people for twenty years. At the end of the day the people are far more important than the monetary stuff. (Although the company stock in my retirement plan worked out really well!) Like any other job, there were times when I had to take on things that I probably wouldn't have chosen, but I was fortunate to have a boss that encouraged me to persevere and succeed. It sounds a little corny, but I'm glad that I was able to stay in this job straight through until retirement, and will always appreciate the smart and kind people that I worked with over the years.
Cons
When positions open it sometimes takes a long time to fill them, which can result in other people "temporarily" (sometimes for a year or more) taking on new responsibilities until a replacement can be found. For employees on salary there are sometimes lots of unpaid overtime hours, but that seems to be pretty normal at other firms, as well.