Having comparisons with only USA serving cruise lines, I won't rehash the astute review of "robinsandiego" dated March of 2015. different Costa ship but all ditto on the info. Cabin stewards and waiters -- Indian, or Filipino or Indonesian -- all fantastic, BUT they are totally overworked. Too few wait staff, MUCH less than Carnival, cabin stewards serve way too many rooms.
Totally focused on Latin interests, ALL music and lounges and loud deck music EXACTLY the same sounding -- I don't mind Latin dancing once or twice a week, but ALL the time? Center Lounge, 7 nights of two guys playing Latin guitar. Which brings another fall short comparison -- On a 7 night Carnival cruise -- 2 show a night comedy club, with comedians being changed off in every other port, so total variety. Guess Europeans don't have senses of humor (anyway if they had a club it sure would not have been in English)
Italians are about 75% of the cruisers, and all announcements are First in Italian, then German, then French, then Spanish, then English. The PA system sounded like a tinny squack box (and what a bore to have to listen to this tower of babel every announcement)