I really like the concept of an synth that can be freely played with! But I find its learning curve a bit harsh. Even with the instructions, I had difficulties understanding really what was going on. What confused me the most is I think some options enabled by default. Like the random mode and sequential mode: while those are great, having the sounds constantly changing prevented me from analyzing the current setting and understanding what I was actually doing. I think that this issue would not exist if all nodes were constants by default.
But even after figuring everything out, the UI remained a bit messy. Mostly because of branches overlapping on each other. Thus, creating something is fastidious, and toying randomly with everything doesn't give satisfying results either.
However I must admit, it's impressive how it manages to represents so much complexity in a such minimalist way! The tools provides a lot of possibilities, and yet consists only in a series of nodes with numbers, and only 4 modes each. Having no words is as much a problem as it is a strength. And all the issues I've mentioned so far are just natural results of this complexity. This UI has some imperfections (mostly branches and the use of two buttons to trigger a menu), but for what it does, it's incredible!
And in the end, learning it was maybe the most intersting part. As I said, I was first overwhelmed by it. But little by little, I managed to experiment with it, and understood mostly what everything does! Although I'm still not able to create everything I want with it, I'm now able to manipulate it to make some very simple sequences of sounds! And in the end this was a nice experience!
So... I think that what the games needs the most is a tutorial. Having all the complexities and too many options right at the beginning is really confusing. Maybe unlocking them step by step, with some goals or puzzles (usually I'm not a fan of those, but here I think it could be really satisfying to try to reproduce a sound), could help the player familiarize with the synth, and enjoying the pleasure of mastering a complex tool.
Anyway, it remains a beautiful musical system! Maybe not easy to use, but still really clever.