Just came back from my first Costa cruise and comparing with Royal Caribbean, this is definitely way below...Just to summarize:
*Bad service overall, worst attitude I've ever seen on a cruise ship. People unhappy, just walking around without a single hello. Had to clean a table many times to sit down, even though employees were close by, they didn't bother. Once, I asked them and they told me "well, we are busy, so it's going to take some time"...no need to say, I did it myself.
*Food, just ok