Amazon CEO stated in the interview where he unveiled the hex copter that it's design is specifically for sub 30 minute delivery of packages 5 lbs or less (86% of what they sell) and only within 10-20 miles of the fulfillment center.
He said they have them, they work, are completely autonomous without needing anyone controlling it, they just need the 2015 FAA guidelines to start flying them and expect to see them in around 5 years.
XI Wiki


