I like it. Could use a little more contextual help and maybe a demo. Maybe bootstrap an interface that is great and let me then start fiddling with it. It was slow in my browser at first and I thought it was broken, so maybe some preloading would help.
I'm working on this browser-based interaction prototyping tool. The goal is to provide a a simple workspace where you can brainstorm and build clickable prototypes quickly and easily.