This criticizes promises on two grounds: they need to propagate and handle errors, and the Javascript syntax looks different from the corresponding sequential code. OTOH with channels, if I understand it, the system needs to propagate and handle errors ("If an asynchronous process writes an error onto its channel we will convert it into an exception") -- can you explain the advantage? And the better syntax we're offered is ClojureScript or yield.

For a cleaner comparison we should avoid unnecessary differences in the code. Let's fix that:

    getTweetsFor("swannodette")
      .then(function (tweets) {
        return expandUrl(parseUrls(tweets)[0]);
      })
      .then(httpGet)
      .then(
        function (responseBody) {
          console.log("Most recent link text:", responseBody);
        },
        function (error) {
          console.error("Error with the twitterverse:", error);
        }
      );

Besides yield, ES6 has shorter function expressions (you can try them right now in Firefox):

    getTweetsFor("swannodette")
      .then(tweets => expandUrl(parseUrls(tweets)[0]))
      .then(httpGet)
      .then(responseBody => console.log("Most recent link text:", responseBody),
            error => console.error("Error with the twitterverse:", error));

I'd agree that this could be better still; I'd like either built-in syntax dealing with promises, like E had 15 or so years ago, or something more general like Haskell's do-notation. But yield seems nice too.