If you will eat a TS meal each day, the DDP is well worth it. The cheapest TS restaurants are the character buffets--cost $28 per adult plus tax and tip. The DDP is $38 per day and includes the tax and tip. You only have to spend $4 on a CS meal or snack item to break even. If you eat anywhere other than a character dinner it is more expensive.
We had several bills from Le Cellier, Les Chefs de France, Coral Reef, etc. that were in the $110-115 range while the plan cost us $76 for 2 adults. So, we "saved" $35-40 without counting our counter service or snack meals that day! However, reality is that we would never have ordered 2 appetizers and 2 desserts except that they were part of the plan. But...the entrees alone were in the $28 each range and more.
So...financially it is a great deal IF your family will eat one TS and one CS each day. It is easy to do a little sharing and have more than enough food on the plan for all meals. If you like only signature restaurants or if you want a character breakfast and a TS dinner each day, the plan may not work well for you.
The other big advantage to us was the freedom/flexibility. Since it was part of the plan, I didn't cringe when my teen wanted some really expensive stuff. She could enjoy herself without the old cheapie mom (me) worrying about it.