I don’t have time to explore Outlook.com fully right this moment, but initially it looks pretty refreshing. The main shift here is that Outlook.com is not conceived of as solely a hub for Microsoft services but as a harness for multiple services (of which the MS services form a piece). For example, you can Facebook chat in the sidebar, or tweet from it, as below.
This harness + MS services approach has been the recent direction of Xbox development, and is (from what I hear) the focus of Windows 8 as well. It’s also the sort of thing Microsoft has a history of doing well — the success of early Windows was, I think, partially due to the sort of intuitions on display here (people bought Windows, after all, not because they loved Windows, but because it worked with the software they wanted to use).
It’s the right direction for an email client looking to become a communications hub, and in line with Microsoft’s strengths as the original platform-focused company. More soon.