It integrates with Word, Excel, PowerPoint, etc as if you were using OneDrive locally.

15 GB of online storage is included for free with all Microsoft accounts. When you first sign in and open OneDrive on Android you're asked if you'd like to sync your photos and videos for an additional 15 GB of storage. You can access your files from any device, including the Web, PC, Mac, Xbox and most mobile platforms.

When Android, iOS and Windows Phone users shoot a photo with their phone it is automatically uploaded to OneDrive via app.