It's here! Microsoft Office is finally here! Well, sort of. Following a similar release on the iPhone several months ago, Microsoft has released the official Office for 365 app for Android, as promised. It's a companion application for their cloud-enabled Office subscription service, and in order to use it, you'll need to be an Office 365 subscriber - plans start at $60 a year for a single user.
Office 365 is only available for Android phones. Tablets aren't invited to the syncing suite party. Microsoft has similar restrictions on iOS, where iPads are left out in the cold. Though they haven't explicitly said so, it's assumed that this is to keep the app as an exclusive for Microsoft's Windows 8 and Windows RT platforms (and the latter could certainly use all the help it can get). Even so, it's a shame: tablets are where one would really want to use this sort of thing.
The app can view all Office documents, and create and edit files for Word, Excel, and Powerpoint. Offline edits are synced to the cloud upon connecting, a nice perk for frequent air travelers. Other cloud features include a list of recently-updated documents that syncs with the desktop version of Office 365, Kindle-style consistent reading progress, a sharing and commenting system, and access to Skydrive and Sharepoint.
Office 365 looks considerably more capable than Google's basic Drive/Docs service, but it's up to you to decide if the extra functionality is worth the price. If you've got access to the desktop and web version of Office 365 through a license from your employer, you should be able to log in without a separate subscription.
Source: Microsoft Office Blog