We tried at work and I found it quite hard to use. The code needed to render even simple things would quickly become unmanageable. My biggest gripe as far as I remember was the structural decision to nest nodes through the constructor which makes it very inflexible and rigid, you can’t just reconnect this bit to that connector, the entire structure has to be recreated. It is also impossible to express it declaratively, which means UI will have a hard time as it can only be done imperatively.
Imo it would help if nodes were flat instead of being nested and connected to other nodes via reference or descriptor, or id. That would make a huge difference. Visual node editors would pop up around that pretty quickly.