The only thing holding me back from going completely to Google Docs is the spreadsheet. For anything real, the Google Spreadsheet is simply not usable. It's a great proof of concept, and it works for small, unuseful spreadsheets, but for doing anything substantive, Excel is several orders of magnitude better.

I don't care if I need to install a separate, native executable/plugin in order to get better performance. If Google offers something that is usable, I would gladly switch to Google Docs.