It is really hard to make the QSDP worth it. If you try really hard by buying the most expensive item (whether or not you want it) and sharing meals, then you can come close to breaking even. You have to be careful with using the snack credits, but don't hoard them because you don't want a ton left at the end. I have heard people say that it is too much dessert (because that comes with lunch and dinner, but not breakfast). You can substitute (like get a water or cookie or fruit for dessert, depending on the cast member), but often those items are less than dessert would have been, so then you are behind. The refillable mug is great if your room is close to that area of your resort, but frustrating if it isn't. I did the ridiculous thing of pricing out all of our meals and seeing how much that would add up to compared to the cost of the plan. According to that estimate, we would have wasted $20 by buying the plan.
I'm one of those people that can't relax on vacation because I can't stop myself from thinking "$4 for a Mickey bar! No way!". Having them be "credits" instead of cash somehow makes it more palatable to me and makes me less likely to say no to the kids and snacks in the parks. This is the all-inclusive feel people talk about.
You really need to sit down and think about what kind of eaters you are, how much you plan to eat, where, and make a guess about how the plan would work for you. OR, just try it out and see what you think. As long as you use all your credits, you shouldn't be out too much money, but you'll be unlikely to be ahead. It's really not a way to save money.
I've even had a place or two put a note on my receipt and I could come back later for dessert.
