I recently started trying out CoffeeScript only to find out that it caused more headaches. The abstraction level of jQuery
Furthermore, any coding language that controls the flow of logic by indentation is extremely dangerous for obvious reasons. I liked CoffeeScript a lot, but the fact that the logical flow of the code is controlled by how much you indent code, spaces or tabs, is not reliable as there is no way the programmer has an easy way of knowing what parts of the code will get hit when the code spans a page.
When I suggested introducing curly braces in CoffeeScript the team, one contributor advised me that my code needs to be re-designed! Needless to say that is absurd. When I included a piece of the code he asked my if it was legacy code. It's like saying to a Java programmer, sorry you cannot use Java because we don't agree with how you write your code.
jashkenas from the CoffeeScript blog gave some great suggestions and made the point that introducing curly braces would be very problematic for them as they use them to denote objects. Makes sense, but I would still love to see some way to replace code flow control with spaces and indentation to something more concrete and human readable.
After running into some more issues with logic errors, try and debug using Firefox's Firebug. Guess what, now that I found the code that needs to be corrected, I have to find that corresponding code in my CoffeeScript file! You guessed it, you cannot debug CoffeeScript, only the generated code and have to work backwards to find the issue in your CoffeeScript file.