Two-Seat Electric Octodecacopter Completes Early Flight Tests (wired.com)

Any explanation of what the advantages are to having so many rotors? Based on a recently-linked article [1], it seems like you'd take a big efficiency hit.

[1] https://news.ycombinator.com/item?id=6730309

Crazy. Zero chances of that auto-rotating you safely down to earth when you lose power.