I is really not at all true that these are only a good deal if you use them on an expensive meal- look at the prices, it is almost always a savings on the things my family likes. Another great savings with these is to buy a child's one and use it for pizza (the kids meal pizza is the same as the adult pizza). We like to redeam our drink or ice cream tickets when we watch Flights of Wonder, mid afternoon. It makes a great break.
Also it does say it needs to be used the same day, but we once left early due to a down pour and were able to use them the next day with no questions asked.
This is my favorite deal in WDW, well second favorite (my absolute favorite is the Taste of Africa tour at AKL, which is free and the feed you). I wish they would offer it in more of the parks...