Pros
Compensation is great, obviously. Fun place to work, and they really take the effort to make the building themes be as interesting as possible, especially in the newer buildings. It's not atypical to be given your own projects early on, but you're encouraged to seek out lots of help since they know you're still learning the ropes.
I also want to address a couple of claims on here that I consider inaccurate:
1) Work hours reported by other people are way over exaggerated. I typically work 40-45 hours a week and based on traffic patterns in and out of the garages, I would say most people tend to work 8-5. If you come in at 7 am, the place is a ghost town, and it's the same as if you stay till 6 or 7pm. Unless they are also working at home (which I RARELY, if ever, do), 40-45 hours a week would seem to be typical.
2) Turnover is not really very high. Of just the 20-30 people that work immediately around me, maybe two have left in the past few months. I've heard the actual turnover rate is under 20%, pretty typical for any company.
3) Travel can be brutal if you're in, say, Implementation, but I only have to travel maybe two or three times a year to meet my requirements, which is typical for most positions (BID, SD, QA, just to name a few). My advice, if you don't want to travel a lot, avoid being in Implementation Services.
Maybe things were different before, but this is how they are now.
Cons
Not too much, honestly, Often times it can feel as if you're given a little TOO much freedom, leaving you unsure of just what you are supposed to do. Sometimes the place can feel a little "cult-ish" and paranoid, but I think it can be justified as Epic has just attained premier status in the EMR world relatively recently (i.e. in the past 5-10 years) and they want to stay that way.