I highly recommend them. I am going to give you a completely honest review. The prices are high compared to going to the store and purchasing everything yourself. I however, have no idea how they compare to other grocery delivery services. They could be comparable. They will go out of their way to get exactly what you want including donuts, a special occasion cake, gift baskets etc.
We placed an order with them for our December 2016 trip. We drove to WDW from Texas and while we were on the way I got an email stating they could not find a soft drink my husband wanted. They gave me alternatives and we choose to just go with basic coke.
We arrived at VWL early that morning - had done online check in so we went to Roaring Forks had breakfast and headed to the MK. When we finally got into our room we called down to bell services and asked them to bring our luggage as well as our Dizzy Dolphin order. They brought the luggage but said they did not have a grocery delivery for us. Needless to say I was a bit panicked. It was just after 5pm on a Sunday. We had dining reservations at 6:30 and I really wasn't expecting to be able to reach anyone at DDD until the next day. I checked on their website and got 2 phone numbers to try anyway. First number I called no one answered so I left a message. The second number was answered right away. I told them what bell services had told me and she reassured me she had indeed left our order personally. She even told me exactly where she put our order down to the rack/shelf number and where in the frig our stuff was. She even told me exactly how many bags were on the rack/shelf and how many were in the frig. She told me to call bell services again with that information and if they still were unable to find our order she would personally call the manager and talk to him/her. So I did as she said and bell services said they would look again in the areas I told them to look and call me back. I got that phone call with apologies and was told they were bringing it right up. I called DDD back and the lady I spoke to was so nice and relieved. She told me she has had this happen before. It doesn't happen often but once in a while it does. She apologized for the confusion even though it was not her mistake. I was very impressed with how professional she was, how quickly she was willing to step in and take control and the fact that I was able to reach a person on a Sunday evening.
We are going back in July and again in December of this year and we WILL be using Dizzy Dolphin once again. We used to just do our grocery shopping ourselves to save some money, but the time saved is well worth the additional cost of having someone take care of this chore for us.