We sailed on the Epic 1/21/12 to 1/28/12. We had a very relaxing enjoyable cruise, however, as experience NCL cruisers (6 times) we wouldn't go on the Epic again.
The ship itself is just too large. We boarded into the casino, not the usual welcome aboard we've had on the Jade or the Star. The casino seems to be the focal point of the ship. As non-gamblers, we found this unpleasant. It felt more like we were in a hotel in Las Vegas rather than on a cruise ship. In general, we missed the feeling of being on a ship. We particularly missed the Promenade Deck.
The service was good, in general, except for the front desk finance staff. They messed up our shipboard credit, which I had to call NCL corporate myself to rectify. Cabin stewards were overworked and it showed in the overall cabin cleanliness. Diningroom staff was consistently excellent as well as the bar staff.