Just got back last weekend from 4 nights at SSR. We did the DDP this time. Final tally showed that we as a group saved about $170 total. We had 3 adults (and 1 infant) in our party - DDW and DMIL.
We ate table-service (dinners) at Spoodles, Chefs de France, and Boma (AKL). The quick-serve lunches were at the Liberty Tree Tavern (fish & chips place in MK), the Chinese place at EPCOT, and the Earl of Sandwich in DTD. Every meal was superb. The bill for Spoodles was $160 for the three of us alone. The only one I wouldn't plan for the next trip was the Chinese place - not that the food was bad, just that it wasn't something that you couldn't pick up at any Chinese restaurant in your local area. Overall, you wind up eating more food than you would normally get if you were paying out of your own pocket (so to speak). For example, we wouldn't get appetizers but they are included in the "sit-down" meal DDP. We wound up ordering three different ones and then sharing them to try different things. Same for desserts - we would NOT order them normally, but we got different desserts and shared them.
The thing that Disney doesn't tell you is that for the table-service (sit-down) meals you have to make reservations - which kinda inhibited us because we planned this trip so close-in from a time perspective. Word to the wise if you want to use the plan - book it in advance and then book your sit-down reservations in advance. This requires some planning, but the menus available on-line it makes it worth it. I think for trips you can plan in advance, the DDP plan really makes sense financially. Lastly we were told (multiple times by more than one Disney person) that the snacks included a drink AND an ice cream/popcorn/piece of fruit/etc. We come to find out that it is a drink OR an ice cream/etc. They would ding you for two snacks if you got a drink AND a popcorn. We finally were given the "written rules" (a day into the stay, at the Land Pavillion in Epcot) and sure enough it says ONE item. I was a bit miffed that the package wasn't described better during the reservation and check-in, but we learned from then on about the "snacks" and how to order them. From a financial perspective, the snacks wind up being gravy because we ate our way through the daily expenses pretty much on the sit-down dinners and about half the price of the quick service meals.
All in all, I would say "go for it" if you can do the pre-planning to get the most out of your experience. If you're more the "play the day as it comes" type, then I probably would just use the DVC dining discounts and the AP dining discounts and eat where and when you choose without worrying about DDP price (which I'm that type).