When we used the "discovery magic" in 2000, it was true that you received salad or soup, appetiser, entree, non alcoholic drink and desert. In 2002 they changed it to salad/soup/appetiser, entree, non alcoholic drink and desert. Still plenty of food!
My DH and I would usually split a salad (they'd bring it on separate plates) and share an appetiser. At many places (like Portabello's) they'd add a lobster tail to the entree!
Even at the 2-wish restaurants we found that we'd get our wishes worth - Fulton's was quite a steal on the plan. Taxes and 15% tip are included in the plan. We'd tip extra on the wine we'd order with dinner and usually bring the tip up to 20% if the service was especially good. Our server at Flying Fish was quite touched, he said that those on the plan didn't usually add anything!
1-wish restaurants that were really the deal for us were Chefs de France, Rainforest Cafe and Portabello's.
If you avoid using your wishes for breakfast, character meals and buffets you will really get your wishes worth.
Have a really great time!