Good article at The Atlantic's Quartz site comparing DJI with 3DR. Sample quote:
The UAV industry is a fairly new one, and right now its main focus is on consumer products. That’s partially because it is growing from a consumer base: What has made them possible is the smartphone revolution, which drove down the price on the tiny electronic components needed to turn low-power remote control aircraft into flying robots that navigate, communicate, and sense. While defense contractors were making expensive and powerful drones for the US military, hobbyists were basically bolting iPhones onto remote-controlled helicopters.