Pros
Wonderful work environment. New campus is awesome, but many employees are not located there and feel overlooked. You feel like you are doing important work. Super-nice co-workers. There are some very smart and driven people who work there who really care about the work that they do. They are the undoubted industry leader and their commitment to go above and beyond for their customers is exemplary. Epic has grown significantly over the last few years and I don't see that abating any time soon. Privately owned which allows for a lot of flexibility in setting the company's direction. Judy has truly been a visionary in the industry and is very well respected and liked by everyone.
Cons
Technology is 20th century. Not a good place to advance your technical skills. Even though there are plenty of smart people, the average techie can't hold a candle to a microsoft or google developer. Some people who work there are really below average. I can imagine that given the location (limited talent pool) and the brutal winter weather, Madison isn't exactly the Bay area. Management structure hasn't kept up with growth which is natural for a company that has grown so fast. There seems to a reluctance to have some decentralized control, but that should improve as time goes on.