One of Google's lower-profile apps, this has a lot of value for those who do a lot of work on mobile devices. The app differs from Google's other major office productivity app, Google Drive, in some small but key ways. QuickOffice's main appeal is that it works with Microsoft Office file formats, even if they're not stored on Google Drive. So if you get an email with a Microsoft Office file you want to edit, you can open it in QuickOffice right from the attachment. Using Google Drive, you can only read Office documents, even if they're stored in your Google Drive.