Pros
The work is very challenging and engaging. You have a lot of autonomy, and control over your direction. The vision and culture of the company is strong. Almost everybody you work with is really smart and cares about what they do, and why. The company really is a large group of people who feel that their work can make healthcare better. Epic has such a strong focus on education that I feel one could spend a life of learning while at Epic - from application certifications, to other external seminars or technical certifications. Because Epic does everything they can to hire really good people, a lot of the people hired each month tend to be right out of college (smart/good people tend to not bounce around too much after their first few years somewhere). This means that with the growth Epic has had, the staff overall is young and ambitious. Some may feel "peer pressure" to also be ultra-ambitious, but to others it's energizing.
Kontras
Since the work is engaging, and since Epic hires people who tend to be ambitious, a lot of people get themselves into a position of working a lot more than they want to. If they're unable to approach the job with maturity in terms of understanding when you're burning out, or Team Lead doesn't help you recognize when you're burning out, then.. you'll burn out.