The current specifications are 15 min max theoretical flight time with one passenger, that never as been proved on real life scenario.
Considering that rotorcopter regulation requires 20 min reserve time unless there is an exception the vehicle can even takeoff battery technology will have to double for a 10 min flight time with 20 min reserve one passenger.
Volocopter is a great project and on electrical VTOL is the current "state of the art" but it's very dependent on a massive battery weight to power improvement.
How I know all this, I run a startup targeting the some problem but with a very different approach.
