Microsoft Office Mobile for Android phones and iPhone is now completely free for home users. An Office 365 subscription is no longer required. You can view and edit Microsoft Office documents without any restriction. Office for iPad on the other hand, supports viewing but not editing for free.
Microsoft is likely making this change in response to both Apple’s iWork (free for iOS 7 and up) and Google's QuickOffice (free for Android 4.4 and up).
Microsoft is also working Office for Android tablets, as well as a Metro version for touch-enabled Windows devices.