Pretty bummed about this news, I'm gonna miss it. Sometimes you want to post something just for some of your closest mates and this was perfect for that.
Sorta. Twitter has a more "passive" type of interaction that is different from normal chats, which tend to be more "active" (you have a bigger expectation of replying).
But I'm not gonna complain too much since I can use this a reason to use Twitter even less.