It is a lot of food, and while it's probably not designed to save money, if uses right you might come out a little bit ahead. It does include and appetizer and a dessert along with the entree. We have used it often. We don't usually use it for a QS meal.
For this upcoming trip we are doing a split stay, 5 nights and then 2 nights. We are doing the deluxe plan for the 5 nights, but will actually get 6 days of use out of it because the credits don't expire until midnight on your check out day. So with spreading out the credits over 6 days we will have just 2 meals a day and not have to feel like we are stuffed.
Some people feel like their ADR times take away from park time, not us. We enjoy being able to sit down and relax. The deluxe plan is not for everyone, you have to know your family. DH and DS are big eaters and they feel like royalty getting to order what they like, it's part of the vacation for all of us.