I use it all the time and it works wonderfully! One time, when we were staying at the Polynesian, we had our ToT photos sent back to the resort. When I went to the shop to pick them up, the order was wrong. Now, you have to remember that the package delivery isn't same day delivery. It's usually the day after..so if our photos were taken on a Monday, we were able to pick them up on Tuesday evening. Usually not a big deal. But, in this case, since we were missing a poster size photo, we were concerned that the photos would have been deleted from the day before. But, that Polynesian CM got on the phone, called ToT and talked to a CM there, and explained the situation. Between the two of them, I was able to get my poster the next day!!!
If it's important to you to have a particular purchase that day, you can always have it sent to the park entrance and you can pick it up after about 3 hours. We do that with attraction photos now, rather than have them delivered to the resort.
One hint for you though...don't go to your resort gift shop to retrieve your packages at then end of your park day. You will find the lines to be long with others doing the same thing!! We try to wait until the next morning and do it then or during our swim time mid-day.
Or, you can always have the shop where you made you purchase ship your purchase right to your home. Then you don't have to worry about anything.