I started using it last month, on production code. I work as a Javascript programmer in an otherwise all-Java software shop. I come from a Python background. I really love it.
I have Vim all set up to auto-complete it, to syntax highlight, and to auto-compile whenever I save. The bad news is: No Eclipse plugins, no notepad++ plugins. etc. So the only other devs who can work on it are on Mac and Linux (which to be fair, half of my company are on Ubuntu, but there's that 1/3 of the company on Windows that just can't practically work on coffeescript code).
There's a 3rd party plugin for PyCharm which has coffee script syntax highlighting. And I think WingIDE for windows supports coffee script as well.
I'm using the former. It's usable, but lacks somethings like fixing indentation errors automatically, and auto-completion. Also the default colors under twilight theme are unreadable, so you have to modify those yourself.
I have Vim all set up to auto-complete it, to syntax highlight, and to auto-compile whenever I save. The bad news is: No Eclipse plugins, no notepad++ plugins. etc. So the only other devs who can work on it are on Mac and Linux (which to be fair, half of my company are on Ubuntu, but there's that 1/3 of the company on Windows that just can't practically work on coffeescript code).