Though this level is not as hard as Forgive Me or the No Mercies it definitely has its own abstract difficulty. You either have to think analytically about its structure or get lucky to find the answer.
This a very popular level, and most love the clever trick involved in its solution. Of course, it brings up the very special situation of being "one move off".
The square 1, 2 and 3 are a real great serie. I especially liked that to look at the board and think logic helps getting the solution rather than to work directly on the board.
Insights