MSN (or Windows Live Messenger as it was since ~2006/7) is being replaced by Skype. If you install a recent version of Skype, or I think upgrade to Windows 8.1 it uninstalls MSN/WLM during the installation and you then can't reinstall it. There are patches to keep the MSN/WLM app - it still works, but at some point they'll update the backend and it will cease working. You can merge your Skype account with the Microsoft account you used for MSN and all your contacts etc are communicable from Skype - or use Trillian or Pidgen or something.
Anyway, on topic: I used to use MSN all the time! I was a beta tester and what was known as an 'MSN butterfly', meaning I was auto invited to beta programs for all the Windows Live apps still have the Live Messenger branded messenger bag I got as swag in about 2006. Nowadays I don't have much need, Facebook has overtaken most of my communication, and I use Skype to chat to a few people now and then.