I've used them twice and will be using them again in August. Everything was in great condition and your resort will keep the cold items cold for you. If you want to order any alcohol you do have to fax them a copy of your ID so they know you're of legal age.
It is a little pricey, but for many things, it's cheaper than what the resort will charge. I liked the convenience of having fresh fruit, yogurt and other breakfast items on hand that I couldn't bring from home. I bring my own cereal/oatmeal packs/granola bars from home as they travel well.
It's my understanding that the value resorts will all have refrigerators soon and that Pop already has them. But I would double check before you order anything dairy. You could though, bring a collapsible cooler from home and keep it full of ice in your bathtub.