Hi, Shellie! I have this debate with myself every time we travel. It really depends on your family and the eating habits of the people in your party.
For our family, I can never make the dining plan work. I have had gastric bypass surgery, so I can't eat a full meal most of the time. I have a nine year old who would still be on the children's meal plan, but she can easily eat an adult meal. I also prefer a lot of times to give my five year old an appetizer from the adult menu instead of giving her a steady diet of chicken nuggets and fries.
For many families, however, this is an excellent way to budget for your meals. You can certainly do it more cheaply if you watch at each meal what you are spending and compromise at some meals (ordering chicken when you wanted steak, for example). You can order whatever you want from the menus, and it gives you the freedom from having to worry about ordering items that are too expensive and blowing your budget. It allows you to enjoy some very nice meals without constantly worrying that you'll have to scrimp and save the whole rest of the trip in order to enjoy splurging.
Weigh the priorities for your family. If nicer, sit down meals are going to be a priority (or even if you plan on doing character meals), and you are a family of good eaters, the dining plan is probably a great way to go!
Have a wonderful vacation!