I think the design and atmosphere is very engaging for a casual learning game like this.
However, it's almost too easy. It'd be better if you got extra points or some kind of scoring system for solving a puzzle with as few changes as possible - as it is now, you can just change everything to false in some of the levels. That requires not that much of an understanding.
Also, I found a glitch: After playing through all the levels once and starting again from the tutorial, it wouldn't let me press the switch. It makes the sound effect, but neither the switch nor truth values change.