Pros
As an implementer, you have to learn a lot very quickly. While the nature of what you learn changes, this general phenomenon never stops. Accordingly, it's great for growth. The physical environment is very quirky, the dress code is nonexistent, and the fringe benefits are great. Coworkers are competent and helpful - this is not typical for all companies, especially what one would expect from Epic's demographics. This is a blessing. They put the customer first - employees know it, customers know it. I would certainly work with a company like Epic as a customer.
Cons
Internal management structure is too loose to be consistent or helpful - and this is the biggest source, I'd say, of employees not feeling valued. Management's interpretation of policy varies from boss to boss and it's easy to get screwed.