Hi, Yes I used iConcierge on the Epic when I cruised transatlantic from Barcelona to Miami in October 2013. I found it very helpful.
You have to download it for free from the app store ahead of time, and then when you get to your cabin, you create an account & activate it through the TV inside your cabin.
It was very easy.
Without needing wifi, iConcierge helps you track all the daily going on. There's ports & tours info, Dining, Entertainment, Spa, Bars & Lounges, onboard Shopping, etc.
You can even keep track of your bill through Folio Review.
Between this, the daily sheet that's delivered to the cabin, and the TV in our cabin, we were able to make reservations, watch our bill & plan our days with ease.
I liked not having to carry the paperwork around with me all the time. It was easier just to glance at iConcierge throughout the day.
Hope this helps!