Pros
The best reason to come work for Epic is the above average starting salary, particularly when you take into consideration the cost of living in Madison. Depending on your Team Leader, you may have the autonomy to do your work in a manner that you see fit but this may quickly come to an end if your practice isn't the "Epic way." Many people complain about the amount of hours that they work at Epic and there may be merit attached to these complaints but this has not been my experience. I have found that as long as you learn to say no to you can get by working 40ish hours a week.
Cons
The biggest downside is the lack of solid management. Upon coming to Epic after having graduated with a business degree and running a company of my own through college, I was put under a Team Leader who had not been with the company more than a few years and had little to no management skill/experience. It appears that promotions to management are not based on managerial talent but on popularity and shear number of hours worked. Another downside of working at Epic is that they recruit people (myself included) who have no background and/or interest in healthcare IT. I believe that this is one of the primary causes of their high turnover rate as most of these people didn't want to be there in the first place.