First the very bad: All our 3 excursions were cancelled. With very short notice. (No other English-speaking had booked.) As we are much more interested in the ports, than for example night shows and sunbeds, this made us very disappointed.
Second, bad things of minor importance: 1. Breakfast- and lunch buffet were very crowded. After some days we find places to slip away from the most busy places. 2. Few of our fellow passengers understood English. 3. Coal flakes from the chimney were falling down on our stern-balcony.
Now to the positive (including surprises): 1. Everything in our cabin was of very good quality and function. 2. The English speaking staff saved us from being totally isolated. And they were overall fantastic, both competent and friendly. 3. Food was very good. Both well cooked and high quality ingredients. (my mother was cook to the former Swedish king.) 4. The pool-area on the ship was very attractive, with its levels. 4. The "drink-package" was a very good bargain. Something like 20â‚¬/day for everything to drink. (Except the most expensive wines/drinks.)
Naturally I compare this Costa-cruise, to the two on similiar ships I've made recent years. One was with Royal Caribbian (RCCL), Splendour of the Seas, the other was with Holland America (HAL.) MS Eurodam. And as I see it, all three give you, all in all, similar quality. Costa is cheaper, but have a more crowded ship. HAL offers more exclusive meals. My conclusion is that you get what you pay for. In future, I can choose any of them. When money is no problem, I prefer HAL. But if I want a wonderful ship, I choose the old Splendour of the Seas.