Just a few things ...
The PowerPoint issue that the original poster mentioned was fixed in an update, so make sure that you're up-to-date. The current version, as of today, is 12.1.5.
Contrary to a report in this thread,
VBA is coming back in the next version of Office.
The Spaces issue is known by both us and Apple. Again, make sure you're up-to-date with your updates of both (12.1.5 for Office, 10.5.6 for OS X). This doesn't fix the issue 100%; complete technical details about what's going on in this are here:
risks and rewards. In short, the issue exists in Apple's window code, and it's a big hairy one for them to fix, and they don't have recommendations for what we can change in our code.
The new file format (.docx, .pptx, .xlsx) is a fully-documented ISO standard XML-based format. Since it's XML, you can actually view the contents of your document in any text editor. All of your content will be surrounded by XML tags, but you'll easily be able to read all of your content; all of the information about formatting is contained in the XML tags. This means that other applications can readily support the file format as well, since it's all documented in the ISO standard. That said ... for most end users, this is probably something that you'll never care about, 'cause a file's a file.

If you prefer to use the old binary file formats (.doc, .xls, .ppt, etc), all of the Office:Mac 2008 apps let you set a pref for that to be your default save file type.
Regards,
Nadyne.