CodeCademy lost attention to Udacity. I'm working through the 7 week CS 101 course there with David Evans of UVA. It's a great class - but probably has too much baggage from traditional Uni courses. People are freakin out about grades and deadlines. I wish there there more Peer interaction. The interaction with the professor via the screencasts and quizes are better than older elearning styles. That old style is typified by a 45 minutes lecture recording and a quiz without feedback tacted on the end.
Here is one point - The feedback is too far away. Relevant and Timely must be applied to feedback. I need it right away for it to work. and, it must be relevant to me. Udacity gets the timely, but the relevant is tough, because of the 'One to many' nature of the screencasts.
Ok - that's my update on CodeCademy and Udacity.