CoffeeScript is just for fun
Fair enough. I can't slam anyone for doing something for fun. And no-one has claimed this to be the new best thing or a must-use tool so I'm not going to start my flamethrower without real provocation!
To the author: I think the syntax is nice, the features I can see being nice to have and you've done a really excellent job on the site/docs. In general though, this seems like a huge amount of effort for basically no gain.