Well, we used the Dining Plan and LOVED IT. I think it is well worth the money.
For example, one day, my DH and I ate lunch in Epcot at the Sunshine Seasons counter service. We each got a HUGE turkey sandwich for $6.99, chips for about $1.50, drink for $2.09, plus DH got a big piece of cake for about $3.00, and I got creme brulee for about $2.00. So that is almost $14.00 without tax. And that is JUST counter service. Of course, if we didn't have the dining plan, we wouldn't have gotten the dessert.
The next day at MK, we ate at Columbia Harbour House and we each got a chicken basket with fries for $6.69, a coke for $2.09 and a dessert for $2.49. So that is almost $12.00 without tax.
Anyway... the point is... the counter services ALONE add up quickly! So, I DO recommend the dining plan. Plus, you get to have a nice sit down meal, and not worry about how much it will cost! And live it up... you are at DISNEY WORLD!