The theremin is a fully electronic instrument that could sound like anything at all — so why does it sound so unpleasant?
Modern ones (the Moog ones I saw 20 years ago) have tunable waveforms but still hark back to that original sound.
I like the sound. In the sonic tradition of the cello.
Does this sound unpleasant to you? https://m.youtube.com/watch?v=62lT9XsZVio (maybe it's subjective, but it sounds very pleasant to me).
The comment in the other reply to the parent comment, as well as what I've heard of Carolina Eyck's playing, do sound pleasant to me though.
Katica Illény doing the Star Trek theme https://youtu.be/x0NVb25p1oU