My wife and I have cruised several times aboard Norwegian ships, and have always had a pleasant experience. We even brought a couple (our best friends) along with us on the Western Caribbean cruise aboard the Sun. But I'm afraid that Norwegian has succumbed to the philosophy of making a buck in any way possible. The size of this ship, for starters, make sailing on the Epic a major challenge for people with difficulty walking. It seems as if everything you want to see or do is on the opposite end of the ship.
And my other greatest complaint is that EVERYTHING on board is a price point for Norwegian. You can't turn around without someone informing you that "that will be an additional charge."
We had to go out of our way many times to avoid the "Casino deck". Between the smoke and the noise, that deck was obnoxious.
The restaurants that did NOT charge were few and far between, but we found the servers pleasant and engaging in all of them. One of the venues that we attended with an up charge, the tepanyaki, featured enjoyable food, but probably would have more enticing had it restricted customers to at least the age of 5 or 6. There were several infants and toddlers the night that we went, and the whining and crying was distracting, as you might imagine.
Our room steward was very friendly and attentive. The turndowns and towel animals were greatly appreciated, and we were glad to tip him over and above the mandatory "gratuity".
In summary, I think we'll be sticking to the smaller vessels in the fleet. Our time aboard the Pearl and the Sun were comfortable and memorable. And the mega-ships are too mega for us.