We are experienced cruisers on other cruiselines -- chose Carnival this time because our favorites were not in the Caribbean this time of year.
Bright spot -- the entertainment -- musicians were very talented, dancers at the very good although the shows badly need updating. Party band on deck one night was super but the smoke belching out of the stacks moved us inside. There was enough variety to keep people happy -- jazz, motown, movies and pool & inside games.
Another bright spot was the relaxed, friendly attitude of the crew and people working on the ship.
Cabin was roomy and clean, bathroom was ok with nice hand-held shower spray but no storage cabinets just small shelf over the sink. Our steward did a very good job.
My son's inside cabin was fine except that his smoke alarm would go off every time he took a shower and it would take 15-20 minutes each time to get someone to turn it off. Their only answer to this problem was don't keep the bathroom door open.
On the other hand, public bathrooms were often very dirty -- not enough of them and not kept clean.
The food was just terrible -- buffet had no variety and the food cold. Cold cuts were fatty and tough. With the exception of the lasagna & desserts (very enjoyable especially the molten lava cake) the food was very low quality. Iceberg lettuce salads, uncutable meats, seemed like reheated precooked frozen dinners. I overheard someone at MDR breakfast ask if they could have their sauce for eggs benedict on the side and they were told no, they are premade. The eggs benedict sauce was orange -- not a natural color and I've had it many times on cruises and in restaurants. There were alot of little annoyances such as no paper napkins at the buffet, lots of dirty plastic cups for self-fill drinks. One morning my son & I stopped to bring tea to DH in the cabin and the water in the cup was coming in brown. Showed it to an employee -- he said "oh, thanks".
Also lacking are lounge chairs in shade. On other cruiselines there are many spaces to relax out of the sun. Not on Sensation. There was a tiny spot on the Serenity deck next to the hot tub for a couple of loungers in shade on the whole ship -- very surprising. It was also very noisy on the deck with a loud mechanical hum constantly plus piped in music (not serene at all).
Word of caution -- I slipped and fell on a marble staircase (after 1 day on the ship) in the MDR turning around because the stairway was blocked by a glass gate part of the way up. The Maitre D was nice and helpful. In spite of having purchased Carnival's insurance, treatment at the infirmary was very brief and cursory. I had to come back and ask for bandages to be redone and no information was given in the infirmary about pain later or what to expect with other injuries. No doctor was offered, just a nurse. No Carnival people in positions of authority checked on my condition (guest services people were very nice) despite 3 visits to guest services regarding the injuries ahd pain. I can only think they truly do not care about the condition of a senior who has fallen on the ship. We received an online survey immediately after the trip, filled it out but received no response. Our travel agent contacted them 3 weeks ago but has received no response. In retrospect, I should have asked immediately to see a doctor if one exists on the ship at all.
Another area that contrasts with other cruises -- is the Safety/Muster drill. This one on the Lido deck was the worst one we have attended. The employees were joking around, we couldn't hear well over the Mongolian Wok banging pots around, people were walking around, noone kept track of who attended or not. Just not taken seriously -- you would think in view of the Costa Concordia disaster there would have been a real drill.
And to think we actually paid more for this 4 night sailing than a 5 night cruise on another cruiseline that has a reputation for being high priced.