We have taken several cruises with Royal Caribbean. The staff has always gone out of their way to be of service to cruisers. I would describe service on ships (in particular Adventure of the Seas for Caribbean cruises) as excellent. I would rate service on the Jewel of the Seas as just okay. It was not just one department but the staff in general. The person who took care of our cabin was the one who gave consistently good service.
Dining room: Service was slow and at first the head waitress said no more than "How are you tonight?" Other ships' waiters give suggestions from the menu, place the napkin on your lap, and definitely learn everyone's first name. None of those things happened on Jewel of the Seas. We had to wait for an hour for our meal the first two nights. The other couple at the table mentioned this to the head waiter so after that the head waitress asked if things were all right at each meal (still no learning of names or any real enthusiasm - just a perfunctory asking if things were all right). After the other couple complained about the service in the dining room, the dining room head waiter asked if he could get the person another drink. He said "yes," thinking it was to make up for the poor service. Instead, the bar person said there was no way he would get a free drink and he needed to sign for the drink to pay for it. It wasn't that he just said this, but it was his rude tone of voice that was disappointing. When the head waiter heard of the problem, he was stunned that the person thought he was going to get a free drink. He kept defending himself. We think the head waiter did not understand the US culture of trying to make up for bad service by offering a free drink or a free dessert. Customs and culture should have been part of his training if he was in charge of the dining room. I should also add that our assistant waiter tried to make up for the failure of the head waitress.
Their roles should have been reversed.