Google Docs is a Document writing, editing, and sharing platform owned by Google. It is a legitimate company, and it is recommended quite well (4.5 Stars out of 5 Stars based on the SiteJabber Google Extension)

It's not a scam - it works in the way a writing app should. You format text, use fonts, use tools, print, and share, and all the other usual things. The only problem is that images are annoying - you insert a few images and suddenly they either disappear or they scatter and you have to find where they went. And text boxes are hard to find - you'll have to go on "drawing" and then make one, and then put it in your work.
However, the good thing is that you can share your work easily, and several people can edit the same document at the same time, and you can easily see who added what.
So I'd say it's legit, as you called it, but with a few problems.