Tablets have, historically, been less-than-ideal for productivity. Part of the problem is that developers are still trying to catch up to the new world of connected devices. One solution, as CloudOn demonstrates, is to bring together the best options from various platforms and merge them into a fluid product. CloudOn lets you use what appears to be remote access to Word, Excel, and Powerpoint from an Android tablet.
The app might be best utilized if you have a connected keyboard and mouse at times, as the UI is still very much the Windows-style.