Pros
I like to think of Epic as a company that does what makes sense, and not what corporate conventional wisdom would dictate. Good opportunities for growth, lots of responsibility, good financial rewards, good benefits. I've been gone >5 years, not sure how well mgmt has kept the ship upright given the massive growth. There had already been a loss of stability and culture by the time I left. Epic is a company I still believe in and root for. It's now a "big scary corporation" but I still see it as made up of amazingly bright individuals who are Doing Good and changing the world.
Cons
Work/life balance can (read: will) be an issue. Moreso in certain roles. You will need to manage your time carefully. I would expect that due to growth and apparent turnover rates, that mgmt experience levels are pretty low, and that it's pretty difficult to gain access to bonafide SMEs.