Yes, it is worth the trip. If you have kids they will be in heaven (and will certainly get a sugar high just from breathing the air - it smells so good!). Also, you will feel like a kid again!
Here is the only problem I see....I can't imagine that you will be able to get to DTD, in Goofy's, and out again without exploring something else while you are there.
Mickey's Mart has tons of gifts (cheap) and you could go in there everyday of your trip and find something new. They move the stuff really quickly.
Once Upon a Toy Store,
Lego Imagination Center, World of Disney, and Build a Dino (inside the new T-Rex restaurant) will put you in toy heaven! Plus there are some other very interesting specialty stores. There really are tons of neat little shops.
There is also a carousel and the new balloon ride and don't forget about Disney Quest.
There are also ton's of places to eat (cs and ts). -Including another candy store - I think it is called the Candy Cauldron and it's over on the West Side. Our favorite cs is Earl of Sandwich and T-Rex is our favorite ts at DTD.
If you don't have much time you could go to Goofy's pick a treat and be on your way. But if you have a little bit of time to spend you could really have a blast!