I also agree with the post below re: branding. I went to "Help" to see what they had and it took me to a windows.com page saying "This page doesn't exist" followed by "Hotmail Help". Nice.
Kudos to the Outlook design team for the clean UI that doesn't take long to get used to and is intuitive once you are used to it.
You can also tab between "to:", "subject" and "body" parts of the email by just using tab (tab twice when finished entering email addresses).
I much prefer using a keyboard than a mouse.
But, I do like the Metro UI, though. Clean!