Well, actually, the rubbish powerpoint compatibility of OpenOffice is why I have stopped using it. As soon as you get a powerpoint presentation beyond the trivial it can't cope.
The rest of the suite is more or less usable, although there are some minor issues with the Excel implementation, again with more esoteric features. My take would be as long as you don't do much powerpoint at all, and are only working in an Open Office environment then it is probably ok, if you are in a mixed environment then you will need access to the Microsoft products from time to time. It is a very, very long way from being a complete, viable replacement in the commercial world if the people you are working with are using the real thing.
