The pitch of the blades is fixed (if I believe the photos from their website), so the variations in lift is simply controlled by the variation in speed of the given rotor. This is just like any hobby quad/hex/octo/younameit-copters out there.

That means you can't reverse the pitch to gain angular momentum from a fall, and therefore, implement autorotation like a "traditional heli" can.

You do have multiple rotors for redundancy (in case one of them fails), but that's not going to protect you from a complete power failure of course if that power source is global.

You can increase safety by providing each rotor with its own independent power source.