I chose Carnival because of price/value for what I was looking for in a cruise. I got more bang for my buck than expected. The entire crew/staff was excellent - they went above and beyond to make sure that we all had a memorable experience.
I chose the 5-day Western Caribbean cruise, so I departed from Tampa. Embarkation, and disembarkation went smoothly, considering how many people they had to move. No complaints there. The ship's decor is rather antiquated (Love Boat feel), but everything else was great. Food was good and entertainment was, too.
Excursions promoted by the cruise were great! The guarantee that you wouldn't be left behind should one of the promoted tours return late was a huge relief, as things happen. Excursion leaders were all good and did a great job at giving us a glimpse into the culture and telling us the best places to shop.
Cabin was neat, clean, and served its purpose (as, we weren't in there a whole lot). I traveled with my sister. We had bunk beds and they were comfortable. Two-four times a day, our statesman came and tidied the room, left fresh towels, left towel animals, left ship-related information, etc. He turned down our beds at night before we returned and beds were made when we returned from breakfast.