Just to share my experience using it for work. I was contemplating buying a laptop initially for my wife to work. Basically she just needs to make entries in a spreadsheet for her accounting purposes. Then when the iPad came out, I thought that buying it would make more sense, since we do not need a powerful laptop to use Excel right?
So I tested some office softwares. I have only the wifi version, and my wife's place dun have internet. So need to edit documents offline and sync them back when she got to a wifi.
Here are the softwares tested and my feedback:
Apple Works : Numbers - Pretty graphics, allows to export to Microsoft Excel format, but I never try that. The deal breaker is that I can't export to cloud storage. Need to use emails. YUCK!!
QuickOffice : Pretty graphics, tabs that actually looks like tabs. Remembers your last page viewed. Can store to cloud storage, BUT it cannot edit the content offline. Dealbreaker I'm afraid!

DocsToGo : Worst graphics among the trio, tabs needs some page switching. But it can store to DropBox and edit GoogleDocs directly! And the best part is, when you are offline, you will still be able to edit it! Once you have wifi, you can sync back the changes! Perfect!
hi, i have Quickoffice too. It can sync with Dropbox and i usually trasfer it to my ipad for editing offline. After editing and i get to a place with wifi, i just drag it back to Dropbox to sync. In Dropbox, when you label your file as a favorite, you can still access it when you're offline. How does DocsToGo amend files from Dropbox when it's offline?