When we decided to go we booked on the Free Quick Service discount. This can be a great deal especially if you were planning on staying on site regardless and really worth it if you were planning to use a park hopper ticket. Reason being the offer is only available for certain dates at certain hotels (there is a variety of choices for each level value, moderate and deluxe) and you have to book package with hopper tickers and stay on site.
We did originally think we were going to stay off site but once I started doing some research and since I never had been there nor did I have any idea on how much there was to see and do before planning, we quickly decided that being on site and the privileges associated with it was for us.
The quick service dining plan gives you 2 meals and 2 snacks for each person every day that you are there. You also get a refillable mug that is bar-coded to fill at any fill station in the restaurants. Great to bring back to rooms or take to the parks. There is many places to choice from and you can familiarize yourself with all the choices long before you leave for your trip. I looked up best dining for quick service and on the Disney Experience app or the website you can look at all the menus and pricing anytime. For the best value of the plan try this link. This year they have added 2 alcohol or specialty drinks but desserts are off from previous years. New this year as well is the mobile service. You can use the app on your phone to order meal and sit at table while waiting instead of in line.
I prefer to have the drinks over the dessert. If you don't drink alcohol you could have fancy specialty drinks as drink and dessert. You could use snack credits for actual treats and a lot of treats are shareable. The way the plan works, is say you are staying 8 days 7 nights for a family of 4 you would start with 64 credits. You can use for breakfast, lunch or dinner. You can use 12 credits one day and 4 the next. It's flexible on how you use. The best to do is use snacks for breakfast items like muffins, cereal and fruits. I did bring some stuff from home too like cereal to eat at the hotel and some snacks. Also, if you happen to be there at the Food and Wine festival time at Epcot, you can use snack credits for the food samples too which is nice.
The only place you will need reservations and is a great use of a meal credit is the Be Our Guest Restaurant. Be sure to make reservations as soon as they open. I had a tough time but if you do, just keep checking once a day and eventually you'll get a spot. You can only go for breakfast or lunch for quick service.
Bottom line is the free dining plan can be a great deal. It is paid with your vacation in advance like an inclusive vacation and we didn't have a problem using just credits to eat with. Plenty of food and we had a quite a few left over that we used for souvenirs (Disney pezz dispensers and other wrapped treats saving money on souvenirs) and snacks on the plane. We didn't have to stress out about leaving the parks. We were able to hop to other parks to eat etc. We really didn't need a car staying on site and saved there. If all these things aren't important to you, there is other deals throughout the year. They usually have a Canadian sale for the winter that is for tickets. Throughout year there is sales from 20-30% off. If you are planning to eat at park at all though, and are flexible with when you can go try calculation with plan and see what the price is with other options to compare the savings.
You can start by looking at Disney's website for special offers. Travel agents will have the same special offers but may differ with blocks of hotels and dates. If you would like to read up more on the dining plan, like all the restaurants available and foods this site has some good information.