Got back a few weeks ago - it was me, dh, ds(3) and dd(2). We got the free dining (which was the main reason for the trip) for 3 of us (dd didn't have a purchased ticket cuz she's free so she didn't get the meal plan). Anyway- we thought that free it was an INCREDIBLE deal. But the question is whether or not I will purchase it for our next visit - I'm still up in the air.
First of all - it is a LOT of food - way more than we really needed. Which leads me to believe that some of the cash is wasted. Yes- we could use up $35 per person per day by eating at pricier places, but with two little ones we stuck to character meals mostly (granted - these are expensive if paying - so we certainly got our money's worth). But on a normal, budget-conscious trip - we bring a lot of food - breakfast, snacks, drinks. And usually get a frig and make a trip to the store for lunch foods. This way we actually purchase one meal a day at the parks, plus a few special treats, plus one or two character meals. Would we be saving money doing it this way or paying for the meal plan? It's a toss up. I say take a look at the restaurants you where you want to eat, make a list and see if you'll be spending the price for the meal plan to eat at these places anyway. If you're even close- go for the meal plan.
In my situation it would actually work best for my family if we were allowed to purchase the meal plan for 2 of us. As many have said, we split a lot of meals and still had enough food - so that would be perfect. Not sure if they let you purchase for some, but not all, in the party.
Good luck and have fun.