Not at Disney yet, but I use them here at home from time to time (Maryland), and have used them twice in Phoenix (when staying at the Marriott timeshare and the Four Seasons timeshare).
I plan on using them next trip to Disney, since they have lower prices than Garden Grocer, they offer beer & wine, and I've been happy with them in the past.
Let us know how it worked out!
I've already started filling my cart, and my trip isn't until March, LOL!