Via OzBargain here
"Sign in with a free Microsoft account to create, edit and save documents for home use.
A qualifying Office 365 subscription is required to create, edit and save documents for business use."Android linkiOS link
Seems to be like the recent OneNote freebie, online docs only can be edited/created/saved, you can only read
A few interesting comments on the OzBargain site, eg. limited tablet compatibility (Android) at the moment.