GeoIP is still pretty much garbage in my experience, but again I've been using VPN's more and more as my ISP turns into total asshats.

But I think it's fine if you combine it with accept-language with the latter taking greater precedence... and so long as there's an option for the user to change it.

And that's really the key. Automation fails. A LOT! Thus giving the user the ability to override is of paramount importance.