This was our 5th cruise since 2001, and our first on Royal Caribbean. We were anxious to compare with Carnival which we used for our first 4 cruises.
Cabin: This was the first time we ever had an inside cabin. We usually go for balcony cabins, but since this was just an "extra" vacation, we were trying to go on a budget. We only paid $400 a person, and had a $100 on board credit, so it was pretty cheap. The cabin was very small. It was actually difficult to store our luggage (we had 4 suitcases). The carpet was disgusting - in definite need of replacement. The lighting was very poor and there were no "freebies" like Carnival gives you in the bathrooms. Carnival usually supplies you with a disposable razor, etc. You get none of that on RCCL. Considering what we paid, however, I wasn't too upset about the accommodations.
Food: I've always heard the food is soo much better on RCCL. Not true. The dining room food was very good, but no better than Carnival. I'd say they are exactly the same. The buffets were probably equal as well. However, Carnival offers made to order hamburgers, hot dogs, pizza, etc. RCCL cooks these in advance and puts them in chafing trays which I think is gross. I didn't have any the whole trip. My husband had a hamburger which he said was hard. On the first formal night, we decided to take a nap before dinner, but we when we woke up, it was 9:15 pm (oops), so we decided to have pizza. That, too, was gross. Was like a frozen pizza which had sat there for a while. Carnival also offers a "deli station" for lack of a better term where you can order fresh made sandwiches, and they also have a chinese window (at least on some of their ships). RCCL didn't have any of this.