I struggled, then got addicted, then figured it out, then felt omniscient, then 2 levels later it ended. In that order!
I had more fun with this than I would have expected, so simple but so much fun. I think there is some work that maybe can be done with the difficulty curve, but I did eventually start recognizing patterns that gave me a real edge towards the end. Levels 17 and 18 I got on my first try and 19 in 2, whereas the mid levels prior I felt I was just throwing together random combos.
Overall wonderful game that I'm sure puzzle lovers will die for. Make a bunch more levels, throw it on steam and drive off into the horizon :)