My husband and I aren't wealthy by any means and we went to Disney at the end of January and were on the DDP. It was just the two of us and so that may affect what I am about to say, but I don't think it saved us any money. If it did, it was very little. The only thing I found nice was that we didn't have to pull out our wallet and pay for everything out of pocket. So it "seemed" like we were saving money because of that I think.
We used all our credits and had TS meals for dinner every night (Concourse, Coral Reef, 50s Primetime, Whispering Canyon). I added up what we would normally eat and it was about the price of the DDP. Now I will admit that we got more food than we would have normally eaten, but I don't know if that's a good thing
One issue for example, at lunch on the DDP at a CS restaurant we each got an entree/combo meal, drink and dessert. Well I don't really care about a dessert at lunch. So if I would have added up just the entree/combo or drink then it would be cheaper to pay for it with cash. Also, there were a lot of inconsistencies between what places offered what. One place would include a burger and fries as a combo whereas another just offered a hot dog as an entree. Well in that case the DDP is really a rip-off. Because I can tell you that the cost of a hot dog and soda, while expensive at WDW, would have been cheaper out of pocket.
Plus with dinners, we wouldn't have ordered 2 appetizers. With one appetizer, 2 entrees, and one dessert to share we would have been fine. And when I added that up with what we would have eaten for lunch and snack then I MAY have saved $20 for the whole trip. But they try to sell the fact about how much you save when compared to the 2 apps, 2 entrees, and 2 dessert cost of the meal.
It was about $321 for the DDP. a day for each of us on the DDP for a total of Maybe with a family it's worth it, but as a couple it was about an even trade-off.
I didn't mind making ADR's in advance and I didn't have any troubles. I didn't even make an ADR for our trip until January and we left for WDW on January 27th. Maybe it's because I made late dinner reservations and there were only 2 of us and so it was easier to get in with just 2, but we didn't have a problem...but like a previous post pointed out, it was the slow season.