Gave it 3/5. It would get a higher rating if level 16 worked every time. I did it precisely like the walkthrough several times, it's never triggered the chain reaction of lighting the other dark bulbs.
Gave it 5/5, as it is ingenious. However, I wish it was more clear that the puzzle pieces had to fit together. It initially had me confused as to why pieces didn't work until I read a comment that said to think of it like a puzzle.
 "RC Cars"){kind=icon}
 "Light UP"){kind=icon}
 "Continuity"){kind=icon}