Pros
Experience - you're working on high-impact and meaningful projects. The quality and type of work is phenomenal and your day to day is meaningful. I wow'd my interviewers when I told them what I had been tasked with, accomplished, and improved while working there. Coworkers - They were great, made some terrific friends. All committed and crazy smart. Made the rough hours easier.
Cons
Employee Happiness Not Prioritized - management knows the business model and they prioritize customer success over employee happiness. Epic could hire more folks and work them less hard by saying no from time to time, but that's not the case. Work/Life Balance - if you work under 50 hours a week, management will give you more to do. There's no way to meaningfully reduce your travel and there's no shortage of work (with a shortage of implementation staff to boot).