In an old-school helcopter you have, say, one main rotor with a vertical shaft, and one tail rotor with a horizontal shaft. Each of them has complex control mechanisms implemented in hardware: the main rotor has swash plates, and so does the tail rotor (or it has variable speed). The pilot controls the system in a direct and even crude way: a side stick adjusts blade pitch, sometimes via a simple cable linkage. Throttle is kept quite stable much of the time.
In this newfangled bird, we use some combination of GPS sensors, an input which is presumably a touchscreen (with all the associated latency, plus wireless), and a speed controller which has to adjust multiple times per revolution of the rotors. For some information on why this is tricky, start here: http://en.wikipedia.org/wiki/Nyquist_frequency
