The app is pretty much everything I had assumed it would be. Like the existing Office apps for iPhone and Android, the new app includes the ability to create and edit Word, Excel, and PowerPoint files, and it has the same OneDrive integration as the iPhone app.
It's a free download but it also requires an Office 365 subscription. This costs $6.99 a month for a single user license and $9.99 (and up) for a multi-user license. You can find the app in iTunes.