Well, I've played it and reached the heaven. It was an arduous climb, though.
The game starts off challenging, and really punishes you at the 1st level. I've voided twice (one manually), got lucky on the 3rd try. The key here is being patient, and precise - and don't move after you hit the required points, you don't need to. The sound effect for failing was very icky, perhaps a little too icky, but gets the point across.
The second level is also hard, but you get used to the black box's movements. Got it on my first try, and I think this was a bit more enjoyable, once you get used to the controls, and how both boxes move around.
The 3rd level is almost relaxing. Almost; since the clunky (keyboard) controls, and the fact that there is no real depth perception to accurately touch the cubes means that the experience feels like random chance, rather than precise action, which holds that level back. I did passed it on the 1st try, but I didn't felt in control of the cube at all.
For the music... the strings feel quite opressive, especially when it kept repeating, and it was a bit loud... It does creates an atmosphere of desperation, though, which fits well to the game's theme.
That is all I got to say here. GG & Cheers!