CoffeeScript added some useful features, like destructuring assignments, and some syntax sugar for objects, loops, etc... but it also made some choices that in my opinion are bad:

- Making delimiters optional like parentheses, brackets, semicolons... in addition to implicit return statements: makes programs hard to read if abused. Makes code formatters get confused and corrupt your code.

- Not being able to distinguish an assignment from a variable definition: causes identifier typos to become new variables.

This implicitness makes programs error prone in ways that are hard to verify and work with. Plus, needs to be transpiled and you will need sourcemaps.

In the end, the benefits are not worth it, even back during the time it was created.