I actually consider The Plaza my favorite table service location in the Magic Kingdom. Frankly, that says worse things about its competition than The Plaza itself, but I think you will find it worth your time and money.
View The Plaza as a glorified counter service restaurant. The menu consists of high-quality sandwiches and salads that you will not find at a place like Columbia Harbour House of Pecos Bill. The Plaza uses fresher, more gourmet ingredients, and everything feels a lot calmer and more formal than at a fast-food establishment elsewhere in the park.
The Plaza shows its value on scorching, tiring days, when you desperately want to sit in a peaceful atmosphere for a bit and enjoy a light, but tasty, meal. I recommend the strawberry salad and the vegetarian sandwich, which seemingly combines every vegetarian delicacy between two slices of bread. The cheesesteak typically receives positive reviews, too.
Finally, save room for the dessert! The Plaza imports sundaes and other ice cream treats from the parlor next door!
Have fun, and enjoy!