Speech recognition has become very usable for me with Dragon Naturally Speaking (I'm using 9.x). I can successfully dictate (and correct) a 70-page report faster than I can type it myself. (I still prefer to give a dictation tape to my secretary who types at 140 highly accurate wpm.) Dragon can get me out of a jam if I need to create some material in the middle of the night, or some other inconvenient time.
I like to use Dragon for personal, written correspondence as I find myself adopting an informal, conversational style that I never seem to match when writing or typing.
Training is far, far less onerous these days than it used to be.
I can only give you my experience with Dragon in (British) English. I have no idea if it's as good in other languages -- I don't speak any well enough to try.
Dragon is the only current speech software about which I can speak from experience. Although Nuance also offers ViaVoice, I really don't think it's kept up. IBM started the whole thing going commercially, what, a decade ago? 15 years? Then they seemed to let it slip through their fingers.
FWIW, once, I thought the idea of controlling the computer by voice was brilliant. In practice I find it tiresome and not worth the trouble.