After an extensive tablet only beta prgramme Microsoft office is now available for phones as well. MS posted the updates today and also information on how to get the apps. MS has made great strides bringing a full desktop office experience to Android and have now expanded to include phones as well as tablets.
From the MS Office Google+ community
The wait is over… you can now download new Word, Excel & PowerPoint preview apps on your Android Phones.
1. Join the Microsoft Office for Android community. (http://aka.ms/phonedroid)
2. Once you join the community, you can “Become a tester” by clicking on the links to the apps: Word (http://aka.ms/previewword), Excel (http://aka.ms/previewexcel), and PowerPoint (http://aka.ms/previewpowerpoint)
3. Wait for Google Play to replicate permissions (this may take ~up to 4 hours), then click above mentioned links and follow the download links to install apps using Google play store.
If you run into any installation troubles, please consult Installation FAQs: http://aka.ms/installfaqs
It is worth noting that some of the more advanced features are only available to Office 365 users.