Docs Viewer is fine if all you need is to view Office documents, but it has some very bizarre design quirks. When there are other Office apps that let you edit any kind of document in addition to viewing it, it's very strange that this app doesn't offer more. It might still work for you if you're limited on space and need to view a file, though.
This app lets you view any file saved in the usual Office formats, including PowerPoints, Excel spreadsheets, and, of course, Word documents. It's limited to just those formats and won't let you edit the documents, of course, but it displays most documents without much difficulty. It presents your documents in a clean interface, so they're easy to read, as well. The app's file menu is the traditional menu you'd expect. Docs Viewer doesn't work unless you have an Internet connection, which is confusing when you consider the app doesn't offer any immediate ways to interact with documents you've saved online.
That's a big downside to this app, because it makes it less convenient for commuters, when other apps have a perfectly capable online mode for people who need to access their files on the go. As is, Docs Viewer isn't much more than a good interface to see your files. If it added some more features, it might be able to compete with other Office software.