I think it's really nice! Usually these flow-chart languages have difficult UI, but this one is pretty easy to mess around in.
It would be good if, while clicking and dragging a new connection line that will replace an old one, the latter's line is dimmed to indicate that it will disappear. Also, those blue nodes need a distinguishing selection color.
It sounds like you're aiming more toward a fun tablet-usable interface, but:
Have you thought about what it would take to write large programs in such an editor? For small fun programs a graph visualization is cool, but larger programs will tend toward a nested indented structure (like existing text) for the sake of visual bandwidth, readability of mathematical expressions, control flow, etc.
Use the arrow keys to move the box around. I suppose that's still a bit primitive, but I'll make some more involved programs once I fix up the scoping model a bit.
When I first started on this project, I thought at some point I would need to make a "zoom out" feature, because you might end up making a lot of nodes in one function. However, I have never needed this. As soon as you have too much stuff going on, you can just box-select some things and hit the "Join" button to get a new function. The restricted workspace actually forces you to abstract things more, and the lack of syntax allows you to reduce repetition more than would be practical in a textual language.
For example, in textual languages, reducing repetition often requires you to introduce intermediate variables, which could actually make the program's text longer, so people will avoid doing it. However, in my language you get intermediate variables by connecting two sinks to the same source. The addition in program length hardly noticeable.
It would be good if, while clicking and dragging a new connection line that will replace an old one, the latter's line is dimmed to indicate that it will disappear. Also, those blue nodes need a distinguishing selection color.
It sounds like you're aiming more toward a fun tablet-usable interface, but:
Have you thought about what it would take to write large programs in such an editor? For small fun programs a graph visualization is cool, but larger programs will tend toward a nested indented structure (like existing text) for the sake of visual bandwidth, readability of mathematical expressions, control flow, etc.