We've done this several times, both before and after it became a set price princess meal.
The food used to be great with choices like prime rib, delicious rolls, salads and several dessert choices. Not any more. The appetizer isn't worth the trouble -- a couple of pieces of cheese and a carrot stick or two. Prime rib is, of course, no longer available. Entrees are passable and desserts are a disappointment. There are no rolls.
Service used to be superb at lunch. Now it's run of the mill as they work to move people in and out quickly.
We still do it sometimes, though, because we enjoy the castle ambience and the princesses.
So -- my current ratings are:
Food = C-
Service = B
Castle Ambience = A
Princesses = A