This was not my first cruise with Carnival, he first was a few years ago in Carnival Sensation (Bahamas), and since then service in general has only gotten worse and worse.
For 5 days/4 nights, there was not one single good meal, not even average, my kids lost their appetite, Breakfast and Lunch were always the same menu in the Mediterranean Rest (Deck 9) which is conveniently located closed to pool area, but everyday was always the same menu, food tasted badly, scrambled eggs tasted like it was mixed with flour, chicken was always dry, every time we ask for something, they didn't have it, for example, my daughter asked for pasta and they said "no, we don't have pasta, if you want pasta you have to go to Atlantic or Pacific and they already closed", I asked for Chocolate Croissant, and they did not have any.
My cabin did not have soap but a Shower Gel dispenser, I asked for one and the answer was basically, "this side of cabins have no soaps, only shower gel", I asked the lady to bring me one as I don't use shower gel, by the end of the cruise I asked for another soap and the lady said "we ran out of soap, no more soap in ship", she finally found one for me with a "your are lucky, this is the last soap".
In the Dining area, service was extremely slow, my kids were starving and getting impatient while waiting for food, my daughter learned not to eat all the plate or otherwise she would set sick.
During our last day (Fun Day at Sea), there was not one single lounge chair available, I asked to please take more lounge chairs our (they have them all tied up by the Mini Golf area), the gentleman said "we are working on it" and left, I ended up sun tanning on a wooded bench by the edge of the pool, few minutes later, I was surrounded by more guests.
And we cannot forget about the Kids Club, one fellow guest I met by the pool said "my girls went and they said it was lame", my kids hated it, they stayed only once for one hour and when I came back my son said "finally you came to our rescue" (a bit melodramatic, I know), but in general it was not good.
I would never go on a Carnival Cruise again, I have traveled with other lines and I prefer to repeat those and try new destinations.
I hope this information helps as I try to be as objective as possible.