I quite like the autocomplete function in Write, but in Calc it was quickly driving me crazy. It wasn’t hard to find in the help, so I suppose the existence of weblog entries about OpenOffice.org autocomplete (like my own) are mainly about the sentiment rather than about an actual neccessity.
I think things like this are a lot easier to disable in Microsoft Office since XP. But on the other hand, where I tell Office to disable a dozen features the very first time I use it I’ve generally been able to use OpenOffice without disabling anything. In the end I just try to use OpenOffice as much as I can because I like OpenDocument. I don’t just mean the idea, I also think the XML structure and such is better than Microsoft’s competing Office Open XML.