I have a RY30 and even if I didn’t get to use it very much, I’ve always found it very capable in terms of sound-design. As Kalimari pointed out it can be used as a chromatically playable (poly? if I remember correctly) -synth.
One of the reason I bought it back then is that is reasonably easy to do some circuit-bending on it…
and that’s a lot of fun!