Been using it for almost 2 years now, the transition will be a huge PIA. It's a good system, it's just so very different from anything else most people are doing.
Things like the code or trauma narrator, charge capturing and documentation so that patients are billed for everything we actually do, the MAR and the way it's set up-all will initially be very confusing, but eventually it will start to coalesce.
As a super user, be prepared to repeat things multiple times.
And, practice, practice, practice the blood transfusion process. It is VERY confusing- we still have to get the book out each ad every time we give blood, and we've been using EPIC for over a year. I would say those 2 to 3 things-code narrator, trauma narrator, and blood transfusion-were the most difficult, at least in our ED.
That and trying to figure out where to document the little things like wound care, pelvic exams, bladder scans, etc. Not necessarily an intuitive or logical program, but it works.