First let me say that I'm completely perplexed by most of the reviews of the Western Caribbean Christmas cruise as my family (5 adults) had a completely different experience. It was above average from embarkation through the time we arrived back in Miami. I should also start off by saying that I was seriously contemplating canceling our cruise because of the reviews on this site. I'm so glad that I didn't! (and by demographic, according to many of the reviews, I'm EXACTLY the type of person that was supposed to hate this ship - don't smoke, don't drink, don't gamble.)
The staff is fabulous. They bent over backwards to meet our every need and wish - as an example, we were never pestered by the bar staff after the first time that we told them that we weren't interested in purchasing alcohol. This was the busiest week on the EPIC so far - almost 4800 passengers - and you would have never known. The food was plentiful and quite tasty. While you may not have gotten a chair right in front of the pool, chairs on deck 18 were abundant.
The entertainment was a lot of fun! Can't think of an act that we didn't like - although, Paul Scally the cruise director got a little irritating after a while. He needs to find something more motivating to yell than calling out all of the different countries of origin.
Here are some things to do -
Take the "behind the scenes tour." You get to see all of the cool stuff that you're wondering about like exactly how many dozen eggs does the ship use in one week and will they have enough food if we're stranded at sea? Ours was on the second sea day and we signed up at guest services.
Stay up late for some of the parties - particularly the "signature" ones. We met interesting people and made tons of memories.
Get a weeks pass for the spa as it's totally worth a few soaks in the hydrotherapy pool and the sunset view from the deck.
Go off the beaten path in the ports. All of the Western Caribbean ports on the EPIC are safe and you should go explore beyond the ports. We highly recommend Rony's Tours in Roatan and just renting a jeep in Cozumel and driving around the island - then stop at a beach north of the port for a drift snorkel (you can drift more than a mile with no effort at all!)
My advice - don't go if you're basing your vacation decisions on the size of a sink, the shape of a cabin or the chance that you might have a glitch on a seven day vacation; however, if you see a sink and think "it's just a sink and it's crazy to think that i will let it make or break my vacation;" or the shape of the cabin is irrelevant because you're there to be outside your cabin experiencing all that the ship has to offer; and you're willing to accept that the chances of having any issue-free seven day stretch in your life is slim to none - then you're ready to leave your house and go on vacation. Might I suggest the EPIC.
As an aside, I have been a little disappointed to read some of the "western world privilege" that comes across in some of the reviews on this site - like "the ports are so poor and nasty" and the "staff doesn't speak English." Those are broad generalizations that I believe reflect American arrogance and part of the reason that a lot of people around the world hate to see us come. The fact is that many cruise ports are in developing countries and by western standards are poor, but might I suggest that the western way of life represents the way that about 1% of the world lives. Also - if a quarter of us spoke another language half as well as the cruise staff speak English (sometimes their third or forth language) the world would be a better place.
One last thing - read reviews with a grain of salt. They represent the opinions of people with whom you may have nothing in common.