"Introducing Outlook.com - Modern Email for the Next Billion Mailboxes"
"Outlook is designed cloud first, so all of your mail is always available wherever you are. Its fresh, clean user interface gets the clutter out of your way-the header has 60% fewer pixels and there are 30% more messages visible in your inbox that the webmail most people are used to. And there are no display ads or large search boxes that take up extra space."
"We saw an opportunity to make email better by using your connections on social networks to enrich your email experience. And so with the Outlook.com preview, we are giving you the first email service that is connected to Facebook, Twitter, LinkedIn, Google, and soon, Skype, to bring relevant context and communications to your email."
So far, I'm enjoying it. Really fast for me.
Even the ads look nicer.
EDIT: The Verge goes into nicer detail with better pictures.