Overall, I would rate the resulting experience as average. We had cruised Carnival once before about 14 years ago on the "Ecstasy". The "Miracle" is enjoyed by many repeat travelers but we couldn't get excited about the operation and ship. The dEcor reminds me of an old gaudy Las Vegas casino. No one started boarding in New York City till 1430 because the ship had to be cleaned due to a threat of illness picked up on the previous trip. The day before embarkation we received an email telling us that we would not stop in the scheduled Grand Turk islands because of a gastrointestinal illness reported. The senior crew would not talk about it when asked. No compensation was offered for missing this stop, not even a free drink. If you like drinking, gambling, playing games like "bean bag tossing" or bidding on overrated art then you would probably enjoy this ship. Very little offered in the way of intellectual pursuits' such as classes on computers, area history, etc. A local Panama speaker came on board and gave information about the transit of the canal from the bridge if you were in a location to hear him clearly. That was positive. Library was very limited and is turned mostly into an internet cafe. Finding world news was limited to CNN and a Florida station on the cabin TV. Nothing else unless you're willing to pay for it off the internet. Internet speed was the usual "slow" experience of shipboard. Better if you try late at night or early in the morning. The last few days the reliability had dropped and you often couldn't get online at anytime.
Entertainment was not up to the same level as Princess and even Holland America. Maybe it's just me but on-board communications was hard to gather. We missed setting our watch back twice in 14 days and the second time I went back to the "Fun Times" daily newsletter to find mention of it. Yes, its there in very small letters on the bottom of the front page. On the day of disembarkation, we waited in the theater for our "zone" to be called which was a designated waiting area. We were told they couldn't connect the communications info into the theater system. Wow, wonder what would happen in a serious emergency? Finally, they moved a staff person down to the theater with a handheld radio.
The average age of travelers seemed to be about the same as most cruises but body weight seems to be increasing. OK, I'm about 20 lbs overweight! The number of wheelchairs and scooters seemed acceptable and most were polite and not coming across as the world owes them something.
In short, we felt that the working crew did their job well and were ready to help. The senior crew would probably be up front in the waiting line for the lifeboat if the need presented itself. You get the impression they have been instructed not to talk much about things the "public doesn't need to know" like past ship episodes in the news. As a Carnival shareholder I own shares for the benefit it offers to the family of cruise lines under its ownership, otherwise I would not own it.
Food was good to start with but started to get redundant after one week. Entertainment was fair, nothing outstanding.
If you were only looking for sea going transportation with reasonably good food at a good price you could enjoy this line and ship. You must be willing to beat off the constant request to unload more funds from your bank account.