I have never received a key response from O&O at my normal ISP-bound email address: there’s something about it that their environment doesn’t like (or possibly something about them that my ISP’s environment doesn’t like and simply discards without notification, but that would probably not explain the problems that others here are having). Using Gmail has always worked for me though.
The main thing that their product offers that good free disk imagers usually don’t is the facility to restore to different hardware. I haven’t tried that, but if it’s implemented competently (i.e., such that it restores working and activated operating systems and third-party applications, which in the case of the latter might require restoring disk and partition IDs) it could be a life-saver.