Unlike many users I jumped into Codecademy with some background and experience. I was already familiar with concepts like loops and arrays. However Codecademy helped me learn them in new languages. I also had the luxury of not having to learn HTML and CSS since I have been using them for a long time. In spite of this, I do not feel Codecademy babied me too much. It was easy to breeze through sections I was familiar with and spend more time with the ones I was not. It seems the site is great for beginners and intermediate users alike.
Yet Codecademy suffered from some bugs. First the Safari browser in Mac OS X the would hang and crash when I attempted to view the Q & A section of the website. This was remedied when I later switched to Google Chrome. Secondarily, over the past week, they had a database problem and I lost much of my progress in my jQuery unit. This was disappointing, but Codecademy lets you skip to lessons you want to take so it did not impede my progress once it was restored. Finally, on some of the lessons, I would code a functional solution but the software would not accept it as a right answer. For those units I had to read the Q&A to learn the trick to move on.
The best thing about Codecademy is its presentation is simple and friendly. An explanation and instructions appear on the left, a code box on the right, and for the most part you are spoon fed your answers. The method is they explain the concepts and then through the process of doing you experience the power of the code. You get multiple tabs like a result window and the in-browser code editor even provides code completion. When the code in the editor auto-completes the cursor will merely move to the right if you type the same character that your cursor is to the left of.
So far my favorite lessons have been the API ones. It is especially gratifying to use the Twilio API to send your cell phone a text message or make a voice call. After doing a couple of the lessons it is easy to recognize how much power sits behind different online platforms and brainstorm ideas for web applications.
Overall I would highly recommend Codecademy to anyone interested in learning to code. It is a fantastic place to get started or for a rusty person like me to brush up on their skills.