I found it particularly difficult, couldn't get past stage 5 of Normal despite a dozen tries. Then again, maybe this type of game isn't for me. I think the lack of an undo command and the speed of the die get unnerving after a few unsuccessful tries, sometimes I know I got no movements left, and I gotta still make the die roll somewhere to fall into oblivion, slowly.
I liked the music though it felt repetitive after a short while, I think a bit more variations are in need. Perhaps a more upbeat part? Also, the menu could have a different song, or a slightly variation of the default music.
The game is solid, just seems to lacks more variations and mechanics. I couldn't progress much so maybe on the Hard levels there are some more twists. It could also benefit from sound effects, like when you finish a level, or a falling sound when the die goes down. I like that you added the rolling die visualization for planning, but I didn't use much of it, as even with it seemed hard to plan movements. I just stuck with the sum of 7 on the sides and planning 1 or 2 moves ahead. Personally, I'd like the die to move/fall faster, maybe this could be a setting?