[lollipop25]

> This means we never know where a function is being called from.

Not really. Chrome dev tools has an "async" option which allows the stack trace to follow through async calls. You will see the async caller instead of the async execution mechanism in the stack. Further, you can black-box frameworks so you only see your code.

> The danger I see with promises is they can be used incorrectly.

The real danger of promises is the different implementations that existed beforehand. For instance, jQuery promises weren't standards-compliant. Their implementation of `then` (which came from `pipe`) wasn't the same as the native one. Getting used to one, you'll easily write wrong code for the other.

> generators will provide more fine-grained control.

Depends. It's a foreign concept in JS, making it harder to follow as opposed to promises which are nothing more than stateful objects. Also, one's mental model will change with generators. One has to look out for that tiny `*` to know the code is "generator friendly".