I think Outlook 2007 is terrific.  There are some great new features and for the most part, you can tell that the developers put tons of effort into usability.  But I do have one complaint...

When I expand the Folder List, I would expect that I could drag one of the folders from my mail store to the little "shortcut bar" on the left (I don't know what it's really called, so I indicate it in the picture here).  My expectation based on some other functionality in Windows and Office and such is that it'd create a shortcut.  It doesn't.