A few thoughts
1. The levels with the black squares and white dots - brilliant and new concept.
2. If you've done other puzzle that involve pipe swiveling, you'll get the idea of things. But many levels involve swapping tiles. Look at the last image: those levers rotate the entire faces from the cube. Complicated.
3. Like the game Hook, "klocki" does not have ultra hard levels. This is the type of puzzle that will lure in non-puzzlers.