I really like it! Very easy and intuitive.
I'd start by adding undo support.
I think next I'd want some way to bring the sections closer together, the gutters feel huge.
And then I'd want some way to drag and drop the sections so I could re-arrange the shapes without having to re-draw everything.
The Chart gallery seems like it could be a more general "placeholder content" gallery. For text, images, chart etc.
Can't wait to see it evolve.
