The app itself is currently quite simple. You can load most of the core modules, like
net, but executing code removes it from the editor. It's literally an interpreter -- a GUI REPL, rather than a way to write Node on the go.
It includes browsable documentation, so you could use it to verify ideas, or more importantly to help you learn Node. It has a lot of potential as a learning tool -- combined with an eBook it would be a great way to execute examples on an iOS device, particularly as you could tweak the code to figure it out.
This would also let people take back those wasted commuter hours. Rather than playing Candy Crush Saga you could boost your Node skills!