If you ask me, CoffeeScript is simply awesome. Last time I had such a fun time hacking with a new language was long ago, when I moved my first steps into Ruby. But as always, when you play with a new toy, inevitably you get to experience also some rough edges.
I wrote a short blog post about this trap and how to avoid it: Non-primitive Properties, CoffeeScript Inheritance and Class Macros. Hope you can find it helpful.