After taking one Carnival cruise many years ago to Mexico, my expectations were very, very, low. We selected the Magic and Carnival for two reasons - Carnival had the best port itinerary and the Magic is a new ship.
I must say, I was pleasantly surprised and thoroughly enjoyed the experience. We booked an Ocean Suite (7244) which was very comfortable and roomy. The staff was friendly, the food was good (not great, but fine), the entertainment on the ship was excellent for the most part - especially the music in the Piano Bar (Ron).
We arranged our own shore excursions, so I can not comment on those provided by the ship.
The highlight of the ship experience was the Chefs Dinner where twelve guests are hosted by the Head Chef in the galley of the ship for an 8 course over the top meal. A must do.
We also loved the Anytime Dining option - no pressure to get back to the ship for early seating, or getting too hungry to hold out for the late seating.
Some slight downsides - the internet connection was difficult and expensive. The decor was a bit cheesy - fake wood does not do it for me!
All in all, I went in with low expectations and came away pleasantly surprised. It was a good value.