While still something of a novice cruiser compared to many here, this is what I have found:
Just back from Carnival Triumph on 11/3/2011
Main dining room - Food was sometimes above average, sometimes inedible. Can't go wrong with the fish dishes or lobster on lobster night. Shrimp cocktail and panko breaded shrimp is also good. Only yucky fish is the fried..Best dessert I ever had was here - the "diet" Bosc pear soaked in wine. TO DIE FOR! Everyone at the table gobbled one down after they saw mine!!
South Beach Buffet Line (Lido Deck) - mostly disappointing. Again, can't go wrong with the fish though. Fish was always delicious, potato salad always good. Fresh salad every night and fresh melons/fruits always good. Meatloaf was best I ever ate!! Pureed yams - good but not great. Oriental glass noodles..AWESOME! Avoid all other red meats as they are as tough as leather!! Cornbread dressing tasted like glue. Anything with crab in it was gross and tasted old. Bread always tasted day old, bland..on the hard side. Desserts were always delicious!! Even the diet desserts!!
Pizza Place - Just tried the Chevre Cheese, sausage and mushroom pizza and it was quite bland..soft crust..blah. Give it a generous 3 out of 5.
Room Service - My favorite here was all vegan..Which is odd because I'm not a vegan. The Foccocia bread sandwich filled with portabella mushroom, sliced fresh mozzarella, baked zucchini and light pesto sauce was a dream!! Nothing Quiznos or Subway offers could ever come close to this explosion of flavor in your mouth! On the side: veggie sticks with blue cheese dressing and fresh fruit bowl (mostly melon). Room service offers all sandwiches (hot and cold) as well as desserts, a couple of salads, tea, coffee and that's pretty much it.
Celebrity Century - This cruise was some time back but I do recall the food was a slight step up from Carnival, however..The service was an abomination..I DO remember how we were treated. The presentation is excellent, but overall, the food is still on the bland side. Also, our entrees took forever to receive each night in the main dining room. You could count on dinner taking a full 2 hours. The slight step up in food quality is not worth it for the 10 steps down in service you take (Carnival Triumph was 10 steps up in service in my opinion).