One of the fine thing about email is that (unlike social networking services like Facebook or Google+) it's based on open and widely used protocols that works across service providers. Why would I ever care what email service provider someone else uses? I trust peoples choices. Hotmail/Windows Live Mail is quite nice these days.
Hotmail's got a lot of small neat features now days.
Like Sweep, I can delete or move all the emails from a certain -- or multiple -- addresses in a few clicks. I can even check a single dialog box and make this in to a permanent rule.
If I mark a message as Junk, but they're in my contact book, I get a check box that says "I think this person was hacked!" ... I have no idea what it does, but it seems like a neat idea in theory. Plenty of times I've gotten junk email from someone I know because they were compromised on some level.
And those are just the features I've noticed, because I don't use Hotmail as my primary email contact.
