The Office Preview apps do not get pre-installed during the upgrade to build 10080.
Just open the new Windows Store (Beta) and search for "word" and you can install them from there.
The OneNote Preview is also available now for phones so be sure to install it as well.
You will find the Store (Beta) on phones is now very similar to the Store on Windows 10 desktop.
Upon install all of the Office Preview apps knew my identity.
Since I was using my Microsoft Account the preview programs also automatically pulled in my Most Recently Used list of files from my desktop version of the programs.
When you view Word in full screen the text is quite small and practically unreadable.
Here is the file dialog where you can see the phone referred to as This PC.
Editing a Word document causes the interface to zoom in on that text area which makes it much easier to work with.
The options in the Word Preview app are inline with the desktop/tablet version of the app.
A zoomed in view of the text as I am writing it in Word.
Formatting options are located under an app bar at the bottom of the app interface.
Ownership and sharing dialog.
Another part of the Word app interface allows you to switch between full screen, Share, give feedback and access additional options under the Hamburger Menu.