I used it to describe the behavior of an embedded device (like the boot sequence or the failure modes), it worked great since team mates would simply update the diagrams without wondering about the format. Also people non familiar with Drakon could make sense of it. My impression was: it is easy to model well designed systems and hard to draw convoluted interactions. It felt like a feature, a bit like LaTeX, where it is easy to produce a beautiful doc and possible (with some effort) to make an ugly one. That was just my impression: if the diagram is too complex, you probably should simplify the design.
