One of the things that most people want or need to do with their mobile devices is to be able to create, view and edit office documents (word processing, presentations, spreadsheets). Google Docs works great on Android, and ok on iOS, but sometimes you need to view/create/edit office documents offline or using the actual file.
QuickOffice is an excellent choice for this task. It is available for Android, iOS, Symbian and webOS, with HD versions for Tablets. The free Quickoffice Lite allows you to view documents, but most people will want the full Pro version ($14.99 for smartphone, $19.99 for tablet). There are deals and specials at different times, and the Amazon App Store for Android has offered it as a free download in the past.
QuickOffice Pro allows you to create, edit, access, and share your Microsoft® Office documents, spreadsheets, and presentations - anytime, anywhere. It also allows viewing of PDF files. TheConnected File Manager offers integrated access to Google Docs™, Dropbox, Evernote, Catch, Egnyte, Huddle™, Box, SugarSync, and MobileMe™, so you can access, share and manage files on your device and the cloud.
It turns your mobile device into a full fledged business device. I can work on files anywhere and then have them saved and uploaded to my Dropbox account, ready for me to use on my computer later. With it, I can create, view or edit any file that I need to. It's easy to use and works great. I haven't had any compatibility issues or conversion issues in over 6 months of using it.
I feel that it is a must have app for all mobile devices.
QuickOffice: http://www.quickoffice.com/
Related:
Android for Education resources and apps
Essential Apps and Installs for Windows, Chrome, Android
Alternative: Documents to Go: http://www.dataviz.com/products/documentstogo/index.html
Disclaimer: I did not receive any compensation for this article.