No Office
People aren't avoiding Office 2007 because it's buggy -- I hadn't even heard about that. People are avoiding it because:
a) Office <something older> is good enough.
b) Already have OpenOffice. Why spend $$$ for something else?
c) Ideologically opposed to OOXML and/or Microsoft.
d) That crap non-menu bar. Microsoft and fans' response is generally along the lines of "Oh you're stupid", "You have to learn how to use it", "It's the wave of the future get used to it". Well, having little nearly-identical-looking blobs (a.k.a. icons) instead of text doesn't do it for me, and I know many like me. If Microsoft's Office team doesn't wish to accomodate people like me, then fine, I won't use Office.
e) No Linux version. I wonder how many people Microsoft *assumes* are running Windows (due to sales figures from all those preloaded PCs) really aren't. They're NEVER going to get Office 2007 since it's not available for them.
For me, it's mostly b, d, and e. But c applies too -- I don't like Microsoft's behavior and avoid sending them money when possible.