I bought document to go premium and keynote because;

1) Quickoffice HD does not have power point (Doc to go has it)
2) Quickoffice HD is for iPad ONLY (Doc to go is both iPhone and iPad)
3) Doc to go can open files with password (i can't find any reading on Quickoffice that can do this, but doc to go review shows that can)
4) Doc to go seems more seamless than Quickoffice HD
5) Doc to go 's Powerpoint can't read text box (Yes, its really ridiculous), so i bought keynote. On a brightside, keynote is awesome to use.
6) iWork is the best user-friendly software out there but it is 30 dollars for all three is quite pricey
7) iWork files can't be password locked which can be a drag.
8) No body ever needs to password lock their powerpoint presentation anyway.

I hope my comments above make sense.

Cheers

1. Only simplified chinese characters
2. I believe you can with Document to Go. Numbers/Pages/Keynote is awesome (as native apple app anyway) but not available on windows. I had trouble with doc to go when i use text box though. It just jumbles up?? Not sure why.
3. Yes, plenty. Mostly are paid apps though.
4. Yes, VLC is probably the only free app that does that well. The rest didn't impress me anyway.