It's funny ... When I came to the theremin I read by so many that it is the most difficult instrument to play. I kinda giggled internally and told myself "How difficult can it be?"
I am being honest here, but I didn't think it was THAT difficult to play. I don't consider myself a master, but in less than 6 months, I was able to play in tune and with dynamics several pieces suited to the theremin. I think the problem arise when newbies take on the theremin and try to play things that is just not playable on this instrument. I do dedicate a fair amount of my free time (about 60 to 90 mins a day) to it and I am enjoying the journey. I have had people asking me if I practice 10 hours a day to "get this good this fast". The "this good this fast" is debatable, but to me, my own perception is that I feel that I am slow as a slug, but to other, I "mastered" the instrument in a record amount of time ( I am not even there yet! ). I think one thing thathas helped me to get "it" quicker is that it seems that I have a good 3D visuals in my mind. It is hard to explain, but when I play and i am in the zone, I can "see" myself playing the theremin's invisible strings!