As an avid cruiser, and having cruised Carnival (Glory) last year, I took a chance on another Carnival (Horizon) cruise this year. There were significant differences. On Carnival Horizon they impose a mandatory 15% tip on every drink you purchase, even when you are sitting right there at the bar in front of the bartender. They try to sneak a 15% tip at the candy store Cherry on Top when you are signing for electronic payment simply for ringing up your order.
Everyday I ate breakfast and dinner at the Meridian Restaurant. The wait was long for someone to take your order. The person who took the order didn't bring it to you and the other person didn't know who got what. Mistakes happened daily. The food was cold. For dinner, the dinner rolls were given to us cold as well. We ordered a sangria for dinner and it was the worst we'd ever tasted and we requested a different drink. It was a huge production for a substitution to be given, as the waiter insisted that we would have to pay twice for the "additional drinks". On the lido deck they constantly "ran out of fruit" and there were long lines waiting for more pineapple, honeydew, canteloupe and watermelon to be dished out. Gelato was served daily from 12 to 2:30, which was shut down promptly at 2:30, even when people were still on line and more gelato was left. Very rude.
The worst part was the steward barged in to the room whenever she wanted, as she was knocking. This happened AFTER the room had been cleaned. She would just "check on us" or come to give us a message by opening the door, almost catching us in a 'compromising' situation twice. Even on our last day, she called at 6AM to give us a "wake up call" (that was not asked for) and opened the door at 7:15 to be sure "we were up". We felt rushed to get out, even though we knew we had to be out of the rooms by 8:30.