Google Docs has a feature set more in line with Wordpad (the stripped down word processor that comes with Windows) than Office Word. I can't understand how anyone can use it for anything at all without running into its limitations, so I'm not surprised it's not all that popular outside of basic shared documents.

I would say Works, it’s much more than Wordpad.

The vast majority of documents people write for within Google Docs’ limitations. I wouldn’t use it for a book or maybe a dissertation. But it works great for a lot of day to day internal business documents.

That seems low to me, but I wouldn’t be surprised at all if it’s not dominant. However it has an awful lot of mindshare.