I use EPIC at one of my clinical sites (I'm in school) and I'm finding it pretty decent to use. Probably the most difficult part of the system is learning what parts of it will auto populate the other parts of the system. When doing my prepwork, it took some time to figure out where the data you need is, but once you know that, it's really not too bad at all. Another clinical site that I've been to also uses EPIC and, while it was set up a little differently, I found it also relatively easy to use. Should I go back to that other site, I'd probably be able to easily pick right back up again and do reasonably well.
In my opinion, EPIC is just intimidating because there's a lot of boxes, it can prompt you to add some fields at times, and it (both implementations I've seen) seems to default to charting by exception. At least it's explained as to what's considered "normal" and therefore anything other than that is an "exception."