Bezos said in the new 60 minutes, it will handle payloads of 5lbs, enough for 86% of it's sold merchandise.
Second, this system could be used in China sooner than here, and being tested by a large package delivery:
The technology just isn't robust enough to be scaled up to meaningful numbers - crashes due to mechanical faults are inevitable
The thing has 8 rotors. It needs 4 maybe to fly with stability. It has redundancy out the ass.
Octocopters are good-weather toys. They cannot be flown in heavy winds. "Sorry, no deliveries today, it's too windy". Yeah. Right.
Well, I'm sure amazon will have a zip code system and weather tie-in to mark the where and when availability that shows are hides the "Delivery by Air" button. Since this will be purely a convenience feature with a corresponding fee, it's not a business breaker.
But for me, this type of system would make much more sense in fastfood delivery systems.
Who wouldn't pay a buck or two to have it delivered at the location marked by smart phone GPS, instead of fighting traffic and using up gas/time?