I was on the Epic last week (first time on the Epic, maybe ninth on NCL). Getting to the pier was slow (traffic) but once we were there, the embarkation was fantastic. No lines to speak of, go in, drop off luggage, get our cards, walk on the ship.
The Epic isn't my favorite. The room layout was fine for 2 - if they are married/dating/close. My problem is that it is designed so everyone focuses inside - it is made to feel like you aren't on a ship. In fact, where you should be able to see the water, from the top deck aft, they put up a huge screen where they show nature pictures.
Food in the MDR was adequate, buffet was a buffet, and the specialty dining pretty good. O'Sheehan's is almost always crowded with a waiting list. Hidden gem is the Noodle bar (included).
My biggest issue - the ship is loud. For example, it is designed with open spaces between the decks, so the mid-main dining room, casino, and a bar are all sharing the same area. Unless you have a balcony, you are not finding a quiet spot outside of, maybe, the library.
The Art Gallery had a surprisingly fun 'scavenger hunt' one evening (matching works with clues).
Surprisingly decent climbing wall too (about 5.intro to 5.10b, I'd guess).
Debarkation was slow - halted due to rain, and CBP was slow, but nothing out of the ordinary. Taxis and shared buses are plentiful, but watch out: "we're leaving right now" means "I'll try to get more people for another 20 minutes before we leave."
Would I choose to go on the Epic over other ships, no. Would I turn down a super discounted cruise on it, no.