In my experience it is great - I use it to store a lot of common documents I don't want to carry around on a thumb drive that is easy to lose. However, my use is primarily non-public facing - storing personal documents and the like. I particularly find the spreadsheet tool in Google Drive useful for storing quick calculations I want to access on the fly, such as notes on an ongoing task or budget projections for my personal finances.
For sharing personal documents, I tend to use Dropbox more than Google Drive, though. In my experience people without tech expertise tend to get a handle on Dropbox more quickly than on Google Drive, though it largely depends upon the people you are sharing with.