I agree with above. If you plan on eating all your meals inside Disney, then the dining plan would save you money. The plan for 5 will be fairly expensive if you get it for the entire stay and would only be justified if you ate full course dinners every day plus full counter meals and snacks each day. And the dining plan does not guarantee you reservations to the character dinners. Nor does it guarantee reservations at your preferred restaurants without prior reservations.
We have stayed at Disney hotels twice with our kids and grandkids, 10 total people. Each time we managed to get the free dining plan as part of our hotel package. That is great, and saved a huge amount of money. But you can't get it free staying at FW. First trip we planned a year in advance and my son made reservations for character dinners as soon as they could be made and got what we wanted. Second trip was shorter notice, but still 4 months in advance and he could not get any character dinners he wanted.