Just a comment here, for what it's worth. I had regular hotmail, knew it was going to be upgraded to Outlook, and now that has happened. Outlook seems fine to me, but I see no need to change my email address from XXX@hotmail. com. I have used that for about 10 years since I first got hotmail. If it ain't broke don't fix it.
I also have MSN email, but it is the same "stuff" (inbox, etc., etc.) and uses the same "@hotmail.com" address. (My reasons for having the MSN mail have to do with my internet provider and are not important here.) The MSN mail did not suddenly become Outlook; it is still about the same as it always was near as I can tell. When I need it it is there, via the Butterfly or sometimes kicks in automatically when sending emails that need POP.
So far I have not had any serious problems with any of the above. The new Outlook, as mentioned, is definitely an upgrade!