It saves us money. Maybe not a ton, but I've run the numbers several times against what we have actually ordered, and it always comes out ahead. We are two Disney Adults, and here's our general eating pattern:
Quick Service Breakfast, usually at the resort. I tried eating a granola bar and having an instant breakfast in the room and was starving a few hours later, so we do a solid breakfast now. We do not generally use a dining credit for breakfast, we pay OOP for breakfast since those items are generally cheaper, and then use a credit for lunch.
Quick Service Lunch in the parks.
Snack; sometimes it's a coffee, sometimes it's the sinfully good cinnamon roasted pecans in Epcot ...
Table Service Dinner. Yes, every night. We've tried doing the big meal in the middle of the day, and it just doesn't work for us. This way we spend the morning and afternoon without worrying about an ADR.
I've run it five ways to Sunday, and we still come out ahead. I even calculated what it would have cost on this last trip we took where we spent a day at Sea World and Medeival Times, and it was the ONLY case in which we would not have saved money if we had the
DDP (we didn't), since we weren't on property for the equivalent of two TS meals.
ETA: I just realized that I hadn't even taken snacks into account when I ran the numbers, so we DEFINITELY come out ahead, even if we use the snack credits on a $2.50 pop. Didn't take tax into account either, so the prices I was using for OOP were even lower than the actual cost, making it that much better. You have to pay tips either way, so those are a non issue for me.