I've tried it with many .doc files.
The app says "PStill has trouble- consult PStill's Log"
But PStill is another app they sell: so DOCtor invites you to consult the logs of an app wich you have not used, not even installed
And the only available log (DOCtor 1.1.1's, consulted through the app menu) says the file has been properly converted.
As for me, this app doesn't do its job & is not even aware of it. Or only partialy.