Really broad question. Straight answer - very good.
Disney has a different feeding arrangement. There is the standard indoor/outdoor buffet/feeding trough. Good place to eat when ambiance is the last thing on your mind. A grill on deck serves a good pool side lunch of burgers and hot dogs. Both ships have three restaurants, by different names, to feed the masses plus a specialty restaurant that requires a reservation and definitely worth trying. You rotate through the three, sitting at the same table number with the same people and the same wait staff. Sort of fun, except you will wind up preferring one over the other two and wish you could have eaten all your meals there, unless you like fun, diversity, trying new things, etc., then you will enjoy it.
The "nice" restaurant asks for jackets but doesn't get them. Decor is upscale, wait staff in tux. A respite for adults, kids endure. "Theme" restaurant is decorated in black and white, then through Disney's master of technology, slowly turns into a blaze of color during the meal. Not sure what that does to your digestive system. As I recall, critters wander about. Wait staff are dressed appropriately. Kids love it, adults endure. "Fun" restaurant, and my favorate is called Parrot Cay on both ships, Caribbean theme and decor with wait staff dressed tropical. Steel band and raucous entertainment while you are trying to eat. Kids love it. Adults enjoy it.
Breakfast and lunch are sit down in the "nice" restaurant and buffet in Parrot Cay. Dirty shirt buffet seems to feed continuously, starting with breakfast, blending into lunch. That buffet also has a kids only section, with counselers, that is very popular, and noisy.
The ice cream bar serves a nice fruit buffet in the afternoon to get you to the late sitting, which is really, really late. Never did find the pizza place.
Menu has three courses; starter, entree and desert. Salad is a starter so I ordered a real appetizer and a salad. The last nights chef's specials are the signature dishes from the WDW restaurants. Menus always include something kids will eat.
No midnight buffet, but if you chose the late seating, you will have just finished dinner.
Oh yes, the food is very good, not great, but very good.
More than you ever wanted to know.