Those things are really fun to fly, to make them stable they have lots of gyros and a computer system that keeps it level by adjusting the power of each motor. With all that onboard once you set them up you don't need to do much to keep it in one spot. Unlike a regular RC heli that will usually go screaming off in some random direction if you don't constantly adjust the controls.
I've got a tiny one and it's amazing how they can cram all that radio, gyro, computer, and motor control technology into a little board not much more than 1 inch square.
Reminds me I haven't flown any of my RC stuff in probably 2 years now, just seemed to lose interest in it.