Just back from our cruise on the NCL Epic. Never having written a review before, I will try to address certain aspects of the ship. Remember that these are our humble opinions and may or may not agree with others' experiences.
We have taken 8 cruises in the last two years: 4 with Princess, 1 with Carnival, 2 with Royal Caribbean (one on the Oasis), and this one with the Epic, so although our experiences may not compare to other seasoned cruisers, we will try to address our own personal Epic adventure.
First, the ship itself - it is the second largest cruise ship in the world, second only to the twin Oasis and Allure of the Seas by Royal Caribbean. It is 1080 feet long, or about 130 feet longer than the biggest of the Princess ships (for those who can't picture this, it's almost a half a football field longer). The Oasis and Allure, on the other hand, are another 107 feet longer than the Epic.