The other downside to their antiquated tech stack is after putting in a couple years there, you will still have no marketable skills because you'll be the same as a brand new dev straight out of school. Everyone else will have two years in on either the .net or the java or the web (rails/django/node/html5) or the ios/android tech stacks. You'll still be starting at ground zero.
Further, my best guess is their devs have something like 25-35% annual turnover. That is not a joke. The best part is if you try to leave, your ass will be stuck in Madison WI. There's really not that many tech companies there so you'll have to relocate. They'll brag about paid sabbaticals after 5 years. So few people last that long I'd bet it's one of the cheapest benefits they have.
Finally, they have a comprehensive NDA/noncompete and since it's Wisconsin, it's very enforceable and they can and do aggressively enforce it.
Just don't do it. If you poke around the internet even a bit you'll see legions of disgruntled ex employees.
I could go on; they have this theory that anyone can be trained to code so your interview is pretty much just your gpa. They then put you through a 1-3 month internal bootcamp to train you to code. You can, um, imagine the sort of code this churns out...
See also [5:6].
[1] http://www.glassdoor.com/Reviews/Epic-Systems-Corporation-Re...
[2] http://forums.thedailywtf.com/forums/p/2417/60874.aspx#60874
[3] http://thedailywtf.com/comments/A_Case_of_the_MUMPS.aspx
[4] http://forums.thedailywtf.com/forums/p/2402/60158.aspx#60158
[5] http://www.indeed.com/forum/cmp/Epic-Systems/Epic-Systems-Sa...