Sharing my experience: My mother and I do a "girls long weekend trip" to WDW every year or two. We love to experience the different restaurants and try new things.
We just got back from a 3 night trip (1/3/07=1/6/07) ... not our first trip, but our first DDP experience.
We aren't big "breakfast eaters" so it was nice to use the snack credit for a morning pastry or fruit cup (but I'm not sure it was a very good value). We still had to pay for coffee, so we basically got a $2 or $3 muffin with our daily snack credit.
We found that with the large portions available we could typically share a quick service meal at lunchtime, and the dessert selections were pretty blah (not something I would pay for normally).
The Quick service meal at Tangerine Cafe was very good, as was Quick service at the Mara (our resort's food court). In most places the desert offering was nothing we'd pay for (or want anyway), so it felt wasteful. (we actually threw some deserts away, uneaten)
In general, the table service credit was just more food than we would normally order and the quality of appetizers was marginal. At Restaurant Marrakesh the beef appetizer and chicken were totally dry and flavorless. The entree was good, but the appetizer and desserts were a real let-down. We won't eat there again. (Tangerine Cafe was a much better quality meal for the money!)
We also had table service at Kona Cafe. Appetizers were disappointing. I found the $10.95 "lump" crabcakes to be dry and "fishy." They tasted like something out of the freezer, rather than "fresh lump crab," as the menu described. The potstickers were marginal and the sauce was very bland. Our entrees were both very good - I had the noodle bowl with chicken, mom had the club sandwich. The best part of the meal was the dessert...banana creme brulee and chocolate macadamia nut tart were both DEVINE!
In the end...the dining plan wasn't for us. We just don't eat that much food at one seating and it was unnecessarily stressful to keep up with the credits and "how many meals remain" and picking an item under $4.00 for a snack, and so on... I don't think we saved much money...we probably would have spent the same eating the way we normally do.
We also agree that the overall quality of food at Disney World restaurants has declined over the last 2-3 years. I'm not sure if that is contributable to the DDP or not?
In the future we'll go back to our typical way of snancking and "grazing" as we want to and planning a few table service meals throughout our stay. The dining plan was an okay value--but too much food and too much hassle.