There are very good arguments both ways. We haven't done it but have seriously considered it. If you are ones that usually buy more expensive items on the menu and have a dessert as well, it is a very good deal compared to paying OOP. If you normally buy lesser entrees and don't have a dessert it may not be a good deal.
The last time I considered it I compared what we could get with the DDP and it is a significant amount of eating, it seemed to be an excellent investment. I then however honestly compared our normal eating and ordering patterns and it didn't seem as good a bargain. If we want to splurge on the way we eat, we may do the DDP in the future.
We drive and are DVC members so we can carry a lot of food with us. Most trips we have a full kitchen at our disposal so we can eat in a great deal so we have other options to consider as well. It the coming years with my DW and me doing some "just the two us" trips and staying in a studio without a full kitchen we'd probably DDP those trips.