I've used graphviz for a bit, which is similar in mindset, and I can see myself using this, as a product.
Now I think the pricing can be a little bit too much.
I prefer echo "digraph G {Hello->World}" | dot -Tpng >hello.png
For a stretched example http://www.graphviz.org/Gallery/gradient/cluster.html
Current paid versions are more for bigger teams and companies requiring on premise solution.
I've used graphviz for a bit, which is similar in mindset, and I can see myself using this, as a product.
Now I think the pricing can be a little bit too much.