I looked at Outlook.com when it launched and recently revisited. I connected a couple of my personal email accounts to it via POP3 without issue and started using it. It’s a pleasant change from OWA which always felt heavy. Its responsive but doesn’t give up the Outlook paradigm. It’s comfortable. It can drop all the email into the Inbox or, as I did on this try, create a folder for each account and treat that as the inbox for that account. But it has one drawback for me – in only polls for mail every 30 minutes with no obvious way to force it. There seems to be hack involving forwarding the mail and then having a separate sender account – too ugly to entertain and not something I’d want to coach a non-technical user on.
Overall I find it more comfortable than Gmail (though I use that as well). I’m not making any changes yet, but email remains the last big chunk of data on my laptop that I have to backup and transfer to new machines. I can see if it evolves just a bit more it could work for me. Just not quite yet.