Pros
You will learn a lot about the US healthcare system very quickly while working at Epic. You will be given complex problems to work on, and you will be able to work independently to solve those problems without management breathing down your neck. You will also have the opportunity to work on problems with a lot of really smart coworkers. Epic experience looks great on a resume, and they cultivate useful skills in new hires straight out of college. The campus is nicer than most corporate environments, and everyone either has their own office, or shares with one other person.
Cons
Epic can be pretty insular, and cut off from the rest of the industry. Epic's technologies and methodologies are not used by any other companies, which means you might not benefit as much as one would expect if you switch to a different job. While there are some benefits of the flat management structure, it means that promotions are rare, so if you're planning on using Epic as a first stepping stone in a career that will ultimately lead elsewhere, you will find diminishing returns the longer you stay. There are no clear expectations on work hours, but in general, you'll work more than you were led to believe when hired. Depending on the position, you may be asked to travel a lot, and when you are traveling, you will often work much more than 40 hour weeks. During one trip, I worked over 90 hours in a week, with 7 12+ hour shifts in a row. This wouldn't really be considered rare, so you can't expect special recognition when you're working extra hard. The growing campus means there is constantly construction.