One more thought: What's the weight limit on that service?
You know, all you had to do was read the HuffPo article to learn that. They're looking at delivering packages of up to 5 pounds, which apparently represents most of their orders.
It's too early in all this to start poopooing as-yet-unseen technology. Amazon's not stupid. I'm sure they are taking all the noted concerns into account, as well as concerns no one here has voiced. Amazon hires a lot of smart people, you know.
It may be successful, it may not. It really depends on how well they can mitigate any risks, and whether they can get government approval to fly little drones all over the place.