The ships on Costa are O.K., but the food and service in the dining room is not . Poor selection, quality and taste along with slow and not well trained servers seem to be the norm.
The pricing for Costa is less. but you get less. If you have done much crusing on other decent cruise lines....watch out for this less than special cruise line.
You get what you pay for.....less(quality).
P.S. I have cruised Costa ships for many years.