I have to admit I've only ever used it to translate a paragraph or two at a time.... where I was just looking for the gist of a text.

Not too surprising, considering that for centuries many people well-versed in two languages have made a very good living as translators ... and often having to get delicate nuances across (for poets as well as statesmen). It's as much art as science.

overwriting articles written by humans with machine generated translations. I really don't understand that! But then, there are truckloads of worthwhile texts from throughout history that will never see translations otherwise ... so that's a worthy cause. Over time it may be improved, IF the algos are given feedback that allows them to learn from mistakes.