I just moved over to using Outlook, and I'm recalling why I stopped years ago. Eudora is hardly perfect, but it doesn't have as much baked in stupidity. Consider the default view in the inbox - just the title of the message (possibly with a small preview), and no immediate view of the message. I created some folders and rules, and messages display in this odd two pane mode - with the list being horizontal and left of the message pane - instead of above it. Not to mention that neither pane seems resizable in the vertical direction. Hell, selecting a message doesn't mark it read - I have to do that by hand. - Correction - there's just a slight delay, at least in non-Inbox folders. In the inbox though, it's manual. Bah.
This is actually unproductivity software. Which begs the question, why am I using it? Well, our IT group supports Outlook only - and I don't see any reason to run two email clients on an ongoing basis. Thus, all my mail is now organized there. I'd love to go back to Eudora, simply because it sucks a lot less.
Oh, and a note to Scoble and his cheering about how daring it was to introduce that stupid ribbon? Good gosh man, have the Outlook team make the rest of the experience not suck. When you define UI trivia as daring, while leaving the suckage setting on "infinite", you haven't achieved much.