Quick Summary: A very professional interview process that really tries to "wow" the potential candidates. Overall however, it was my impression that the company gets by on the talent of young recruits (who are dazzled by good salaries and a "relaxed" atmosphere) but weakened by a very likely high turn-around rate; the few long-time workers were nothing special. (To Illustrate: I was most disappointed when one of the technical specialist didn't know what cloud computing was when a question regarding the topic was brought up - not the response you want to hear from a technology company).
The Project Manager/Implementation Consultant interview process is akin to other consulting interviews: plenty of testing, a phone interview, group interviews, a presentation (your choice), and more 1:1 interviews.
After applying online I was contacted within a couple of business days to set up a phone interview and with links to online tests. The interview was fairly casual and lasted less then an hour. I was surprised by how much the interviewer questioned me about my willingness to live in Madison, WI. The questions might have made me think that Madison was a terrible place to live/work, but I had already done research and thought the place to be very nice. The rest of the interview was very generic and seemed like a formality (my guess is that I did decently on the tests and combined with my Ivy League background Epic was interested as long as I didn't completely mess up).
Within a few days I was contacted and told that I was invited to an on-site interview and that an Epic agent would be in contact to arrange my flight plan. The recruits arrive the day before the interviews and are housed at two very nice hotels in downtown Madison (and given the VIP treatment, as all food is covered by the company). There is an optional dinner with current employees that is nice gives you a chance to meet other recruits and pose thinly veiled questions about life in Madison and at Epic.
The interview day starts early and last all day. A good nights sleep is highly recommended. This is especially true if you have not already completed some of the skills tests (not the personality tests). These are technically not timed, but as time counts, you want to make sure that you won't be rushing as I highly suspect that these tests are more important to the HR decision making process than they would have you believe. The materiel covered is a combination of GRE-style questions, some LSAT logic questions, and some "trick questions" that involve some critical thinking. Otherwise, the interview process is pretty straightforward. If you were flown in, I would recommend taking a late flight back so as to not be rushed during your day (which although very scheduled, might be a problem if your flight leaves only an hour after the scheduled end).
Again, Epic seems like it does a good job attracting very talented people but I highly doubt that it retains most of its brightest stars. The overall atmosphere does not seem very professional (maybe professionally casual). The average age of the employees is also pretty young (again likely pointing to high turn-over rate) but I didn't think age was held against anyone during the interview process and by extension while employed.