Ask HN: Friend hit with locky today, does paying ransom work?

Someone I know got hit with locky ransomware today. It infected their pc plus some server drives. Those drives can be restored from backups but the pc is not backed up. I told them I would ask the general community if anyone knows if paying the ransom actually works. Does the decrypter actually work? Hard to trust a crook. Anyone know if the decrypter installed a backdoor? Any analysis done on that yet? Hard time finding anyone on the internet talking about it in this way.