I also had a NetGrocer order delivered to ASMu in August.
When we checked in, the CM was alerted by the reservation system that packages were waiting. They were delivered to our room while we were enjoying our first afternoon at the parks.
It was great to come back to the room to find snacks and juice waiting for us. I brought a fold-up cooler, so we always had something cool to drink at hand.
One suggestion: I ordered too many of the little no-need-to-refrigerate aseptic milk boxes and ended up discarding them when my 8yo lost her taste for milk because of the heat.
A quart of milk from the gift shop would have kept quite well on ice in the ice bucket. I didn't check the gift shop prices for food items at ASMu, but there was a good selection at WL. (We moved there after 3 nights.)
If you check for manufacturer prepriced items (especially baked goods) in the gift shops, you won't pay any more than at your local grocery store. Beer, wine, and liquor (airline-size bottles) were much less expensive in the gift shop than at the resort restaurants and bars, as well.
We had a car, so we were able to make one trip off-site to Walgreens for bottled water. NetGrocer's bottled water prices seemed prohibitive, but then I ended up buying more than enough water at Walgreens anyway.
I love NetGrocer's interface; it applies discount coupons automatically, and there's always some freebie offer. I use them several times a year for staples at home. It's great during the holidays.
gadget-lady