Since we were cruising in January, my main concern was about the weather but it turned out to be dry, sunny and the sea was calm throughout the cruise.
Overall impression of Costa is very positive. We are a family of 2 adults + 1 teen (15 years old) and everyone was kept busy by Costa's staff: the kid was off for the Teen Zone, my husband was into leaning Italian language and I was happy with Latino dance lessons.
The ship is new and cabins are spacious.
Negative: staff look exhausted, there's plenty of smoke in some areas and route was changed twice - we skipped Tunis and Marseilles.
If you wish to ear gourmet cuisine - you can try it ashore. On board food is plentiful and eatable - nothing more than that. No complaints, though!
Evening theatre performances are also far from being top of the range - it's not Vegas, after all! We did enjoy watching it couple of times - no complaints, we booked a cruise and not a theater performance!
If you watch your spending you would not loose a fortune for on board expenses. not cheap, but reasonable.
Would we like to come back? Yes, we definitely would.