I liked the music, art, and overall simplicity of the concept. A lot of variety in levels as well!
I am not sure that removing orbit “notches” later on is the right move, since it just makes the puzzle more tedious rather than mechanically different or logically difficult. You have no way to see which planets a signal can potentially reach (if there is a way, then I missed it) and are forced to spend a lot of time looking for those potential alignments.
So I stopped playing after Cancer, though I am curious how the puzzles evolve later in the game.