Love the game -- hard as nails. Just the kind of thing I'm looking for in a puzzle game.
I admit, I was really disappointed that the characters freed from the jail don't join you permanently; they're hard enough to get that it should be a permanent unlock.
Admit to also being bothered slightly by the floor indicator being horizontal when you're actually climbing vertically.
To me the rat dodge mechanic seems to be hitting at about the intended 50%, though I agree that it's kind of a magnet for Murphy's Law.