My family and I had a wonderful vacation on the Norwegian Epic. There were 8 of us in my party, and everyone had a great time. I have cruised with NCL several times and I actually found the food on the Epic to be exceptional. I do not, as a rule, buy up to the specialty restaurants (my feeling is that all of the food comes from the same kitchen) or do the buffet for dinner. I was amazed at the variety and "restaurant feel" of the "free" dining areas and found both the Manhattan Lounge and Taste to be fantastic. The service received at both was very good.
In terms of entertainment, I found the second city comedy to be lacking (maybe I just didn't get it,) but the Bob Marley tribute was fantastic. The lead singer had a great voice.
I had read reviews that the casino was too smoky, I enjoyed the casino every night and did not experience a particularly smoky environment, although I noted that their were hardly any smokers around me. My only criticism of the casino is that the slots were somewhat stingy. I am always somewhat apprehensive about playing slots anyway on a cruise ship as I am not sure how regulated they are. The table play was great and dealers were engaging.