I will say that it sounds odd. I would have to learn to wrap my brain around that new paradigm. I do agree that you lose customer service, but if you are looking for customer service, than I am sure those folks would have the sense to visit a counter. Well, one would like to think so.
I think it is a great if it's an effective tool for someone who knows what they want and would like it in a hurry.
I worry about the practical issues like: Can I return it? Where? What if the item dispensed is broken? For example, I have an iPod. I know how it works. I don't need help in purchasing it, but if it breaks a day after I buy it - what then? I'm sure they have systems in place, but I wouldn't be happy if they required extra steps.