[Cthulhu_]

In theory, they keep your data private, combine it with the greater learnings of the world, and provide you with perfect autocomplete and autocorrect.

In practice though, it just doesn't work. I got GBoard for a while because it has a bilingual keyboard, but the autocomplete suggestions often ended up being people's first names instead of common words (and not even the people I was talking to).

[jfengel]

I speak French much better with GBoard, because it spells better than I do. It also has a pretty good sense of grammar: it will often autocomplete the correct ending of a verb. (It feels like cheating to use it with Duolingo.)

Of course I speak only simple French, and those are the cases where its primitive learning is most apt. When I speak English, its suggestions are less useful, because I use a much wider vocabulary and more sophisticated sentence structure.