Each person MUST have an android smartphone?

. Might be a problem with apple users?
Also, should the escrow need to have good rep? What if the buyerdecides to not sign the ssignature? It would be up to the escrow, and happens if the escrow was a troll or an alt of the buyer???
iphone solution is in the pieline.
Collaboration between an escrow agent and the buyer or seller is always a risk. So reputation is important for an escrow agent, however with using multi sig it's easier to build a reputation, because your using the right tools int he first place.