I used Cloud9 (pre-Amazon acquisition) for teaching high schoolers the basics of programming. It was super easy to set up and use. It really let me, as the teacher, focus on teaching syntax and principals and less on 'toolchain config', which is helpful for newbies right out of the box.

I haven't used this new Amazon Cloud9 offering, but from the initial impression from the blog post, they've traded in the easy of use that Cloud9 once had for a deeper integration into the AWS ecosystem. The screenshots I saw were not something I'd want a greenhorn to have to walkthrough.

I'm not sure what future I expected when Amazon purchased Cloud9, but I mourn the potential loss of an awesome cloud based IDE that beginners could easily pickup (my mind can be swayed once I give it a try though).