Overall, I had a great time on the Epic and would not hesitate to sail on this ship or Norwegian again.
As big as it is, I never had trouble finding a lounge chair or a quiet spot outside (hint: Deck 18) when I wanted to get away from the crowds. The pools and water park were great, and there were enough adults-only areas, such as Spice H20.
I thought the food was good overall, whether I was eating in the for-fee restaurants or the buffet or main dining room, and I never felt nickel-and-dimed. The entertainment, I thought, was excellent, although I did walk out on the Blue Man group. Second City and Legends In Concert were fun, though. So were Howl at the Moon and the comedian/magician. Slam Allen rocked in the blues club, too. Watching the Super Bowl on the big screen under the stars was pretty cool, too. What I liked is that there was always something going on, whether it was a band playing or a show or a party or even movies in the atrium (I saw the Natural on the big screen for the first time since it was in the theaters).
I had a balcony cabin, and it was perfect for me. The decor was contemporary, and there was plenty of storage. One thing I did not like was the curved couch. It was completely uncomfortable.
I had a few other gripes with the ship, itself. The elevators are a disaster, and smoking in the casino should be banned. It's just inexcusable that Norwegian allows it, knowing what we know about second-hand smoke, and the fact that it's right there in the middle of the ship makes it even worse. Memo to Norwegian: Designate a room or space outside for smoking and ban it elsewhere.