I had a trial version of one of those years ago. It was surprisingly good!
I left the scary Parish Magazine Editor to dictate a long article (she seemed to think I'd be happy to type it at her dictation). I came back half an hour later. The document was finished, but it was well sprinkled with "no, stupid machine, oh I don't know" and the like.
I was impressed with how it would pick a wrong word (seen / scene etc) but go back and correct it after a few more words. She and I learned just to plough on, and correct at the very end of the process.
Then the trial ran out, and I saw the price for the full version!