http://raganwald.com/2013/07/27/Ive-always-been-mad.html
http://lucumr.pocoo.org/2011/12/22/implicit-scoping-in-coffeescript/
http://www.reddit.com/r/programming/comments/1j1cw7/coffeescripts_scoping_is_madness/
I work in Python on the server and JavaScript on the client all day long and I really do think syntax matters.
I would love a client language that was as clean and beautiful as CoffeeScipt but I think this issue is a show stopper for me.