My wife and I love cruising and this is our first cruise. The other 4 couples with us pretty much agreed with us, especially on the cabin. We have been on most cruise lines including 5 NCLs. We plan on sailing on NCL Dawn next January. So as you can see we have no problem with NCL. However, we found the EPIC to seem more crowded than other ships. We have also been on Oasis of the Seas and Allure of the Seas and Freedom of the Seas, so it is not the size itself that made it seem crowded to us. Just to be clear, we had a good time and if any of friends or family wanted to go on it again we would go.
The bathroom layout was also not to our taste! And my wife missed lobster in the main dinning room.
Besides being crowded the balcony cabins are unbelievably skinny. They have wonderful storage space, but if you order room service, which we usually do for breakfast, there is almost no place to put the tray. There is no way 2 people can pass each other either. We have been told by others that the newer big NCL ships are much better.