JD has given us a cool drone frame with brushless motors. It doesn't have a flight controller though. For many drone applications creating our own using open source tools would enable us to use it for proof-of-concept testing platform for drone applications. We already have an arduino and an arduino GPS shield, so we could use that as a basis. There are plenty of good articles on making your own controller using arduino (and other tools). See for instance

http://www.robotshop.com/blog/en/how-to-make-a-drone-uav-lesson-4-flight-controller-15191

http://www.instructables.com/id/DIY-ARDUINO-FLIGHT-CONTROLLER/