The Roli Seaboard is intuitive to understand, but difficult to master, much like a traditional acoustic instrument. I imagine the same would apply to the other Multidimensional Polyphonic Expression instruments (Haken Continuum, Linnstrument, Eigenharp).
Dolores Catherino does a great job of demonstrating the difference between the Seaboard and the Continuum in this video, then goes on to coin a term for microtonal music: “polychromatic”. The reason for the new term becomes clear as she explains her color-augmented traditional notation system. Again, intuitive to grasp, but it would take a lifetime to master the concepts she’s talking about.