I just got home from my cruise on NCL Epic, and I liked it! As a solo traveler, the studios were a perfect fit for my budget. There was plenty of storage space (once I found the baskets under the bed). Granted, the room is SMALL, but I only use it for sleeping and showering anyway. I would NEVER book a studio for two people.
The entertainment was great. I particularly liked the dinner theater options. I saw both the Cirque and the Murder mystery. As a solo traveler, I was seated with other families. It was a bit awkward at first, but I am pretty good at adapting and making small talk. The food was great (it was a set meal, but I like to try new things - so no complaints from me). I know the kids at the table didn't like the meal. Perhaps NCL should consider having a kids' menu for these shows.
The adults' only pool (Spice H2O) was particularly awesome for me. The pool was a little warm and the hot tubs were a little cold. But the benefit of not tripping over little kids was a big bonus for me. I did wander over to the main pools to try out the water slides. They were great fun. One issue (not an NCL problem) was that mothers would wait in line for the Epic Plunge, and when they neared the front of the line, six little kids would appear out of nowhere and the mothers would smile and shrug at me as they let them into line. Needless to say, I only waited in that line once (I was afraid I might voice my disgust towards these people too loudly to attempt it again.) I heard complaints about the main pools and I can see their point. For a ship with over 4000 people, I think the main pools are way too small.